U.S. patent application number 17/414938 was filed with the patent office on 2022-02-17 for random access procedure based on two-step random access channel procedure and four-step random access channel procedure.
The applicant listed for this patent is QUALCOMM Incorporated. Invention is credited to Linhai HE, Jing LEI, Ruiming ZHENG.
Application Number | 20220053575 17/414938 |
Document ID | / |
Family ID | |
Filed Date | 2022-02-17 |
United States Patent
Application |
20220053575 |
Kind Code |
A1 |
HE; Linhai ; et al. |
February 17, 2022 |
RANDOM ACCESS PROCEDURE BASED ON TWO-STEP RANDOM ACCESS CHANNEL
PROCEDURE AND FOUR-STEP RANDOM ACCESS CHANNEL PROCEDURE
Abstract
Apparatus, methods, and computer-readable media for performing
random access procedures based on two-step random access channel
procedures and four-step random access channel procedures are
disclosed herein. An example method for wireless communication at a
User Equipment (UE) includes determining that a fallback timer
associated with a two-step random access procedure is configured
for the UE. The example method also includes generating a random
access message based at least on the determining. The random access
message may be one of a first-type random access message associated
with a four-step random access procedure and including a preamble
or a second-type random access message associated with the two-step
random access procedure and including the preamble and a payload.
Further, the example method includes performing a random access
attempt by transmitting, to a base station, the random access
message.
Inventors: |
HE; Linhai; (San Diego,
CA) ; ZHENG; Ruiming; (Beijing, CN) ; LEI;
Jing; (San Diego, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
QUALCOMM Incorporated |
San Diego |
CA |
US |
|
|
Appl. No.: |
17/414938 |
Filed: |
January 4, 2020 |
PCT Filed: |
January 4, 2020 |
PCT NO: |
PCT/CN2020/070357 |
371 Date: |
June 16, 2021 |
International
Class: |
H04W 74/08 20060101
H04W074/08; H04W 56/00 20060101 H04W056/00; H04W 72/14 20060101
H04W072/14 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 30, 2019 |
CN |
PCT/CN2019/074028 |
Claims
1. A method of wireless communication at a User Equipment (UE),
comprising: determining that a fallback timer associated with a
two-step random access procedure is configured for the UE;
generating a random access message based at least on the
determining, wherein the random access message is one of a
first-type random access message associated with a four-step random
access procedure and including a preamble or a second-type random
access message associated with the two-step random access procedure
and including the preamble and a payload; and performing a random
access attempt by transmitting, to a base station, the random
access message.
2. The method of claim 1, further comprising: receiving, from the
base station, at least one parameter associated with the two-step
random access procedure, the at least one parameter including one
or more of a payload size, a set of payload sizes, a Reference
Signal Received Power (RSRP) threshold, a path loss threshold, a
fallback timer setting, a first-type random access message
transmittal count threshold, or a second-type random access message
transmittal count threshold, and wherein the generating of the
random access message is further based on the at least one
parameter.
3. The method of claim 2, wherein the at least one parameter is
received via system information.
4. The method of claim 2, wherein the at least one parameter is
received via dedicated signaling while the UE is operating in a
connected mode.
5. The method of claim 2, further comprising: measuring a reference
signal; comparing a measurement of the reference signal to the at
least one parameter; and determining to generate the second-type
random access message when the measurement of the reference signal
satisfies a threshold associated with the at least one
parameter.
6. The method of claim 5, wherein the reference signal is comprised
in a Synchronization Signal Block (SSB).
7. The method of claim 5, wherein the reference signal comprises a
channel state information reference signal.
8. The method of claim 5, wherein the UE selects the reference
signal to measure based on a predetermined rule.
9. The method of claim 5, wherein the UE selects the reference
signal to measure from among a plurality of reference signals
received by the UE and based on respective reference signal
measurements.
10. The method of claim 5, wherein the measurement of the reference
signal comprises a Reference Signal Received Power (RSRP) of the
reference signal, and determining to generate the second-type
random access message when the RSRP of the reference signal is
greater than or equal to the RSRP threshold.
11. The method of claim 5, wherein the measurement of the reference
signal comprises a path loss measurement associated with the
reference signal, and determining to generate the second-type
random access message when the path loss measurement is less than
or equal to the path loss threshold.
12. The method of claim 2, further comprising: measuring at least
one reference signal; comparing a measurement of the at least one
reference signal to the at least one parameter; and determining to
generate the first-type random access message when the measurement
of the at least one reference signal does not satisfy a threshold
associated with the at least one parameter.
13. The method of claim 1, further comprising receiving, from the
base station, an indication that indicates whether the base station
supports the two-step random access procedure, wherein the fallback
timer is configured when the base station supports the two-step
random access procedure.
14. The method of claim 13, wherein the indication indicates that
the base station supports the two-step random access procedure on
an access class basis, and wherein the generating of the random
access message is further based on an access class associated with
the UE.
15. The method of claim 1, wherein the random access message is the
second-type random access message, and further comprising:
incrementing a second-type random access message transmittal count
after the transmitting of the second-type random access message;
determining whether the second-type random access message
transmittal count satisfies a second-type random access message
transmittal count threshold if a response message is not received
from the base station; and determining whether to repeat
transmission of the second-type random access message or to
generate the first-type random access message based on whether the
second-type random access message transmittal count satisfies the
second-type random access message transmittal count threshold.
16. The method of claim 15, wherein the determining of whether to
repeat the transmission of the second-type random access message or
to perform the four-step random access procedure is further based
on whether the fallback timer is active for the UE.
17. The method of claim 15, wherein if the second-type random
access message transmittal count does not satisfy the second-type
random access message transmittal count threshold, the method
further comprises: generating the first-type random access
message.
18. The method of claim 15, wherein if the second-type random
access message transmittal count is less than the second-type
random access message transmittal count threshold, the method
further comprises: repeating the transmission of the second-type
random access message while the fallback timer is active.
19. The method of claim 1, further comprising: receiving, from the
base station, a random access response message in response to a
transmission of the second-type random access message, the random
access response message including an uplink grant and information
indicating a failure to decode the payload of the second-type
random access message; and transmitting, to the base station, a
third-type random access message comprising the payload based on
the uplink grant, the third-type random access message associated
with the four-step random access procedure.
20. The method of claim 19, further comprising determining whether
to perform another random access attempt using the two-step random
access procedure or the four-step random access procedure when the
fallback timer is active and no response to the third-type random
access message is received or when the fallback timer is active and
the UE receives a response to the third-type random access message
indicating another failure to decode the payload.
21. The method of claim 1, further comprising receiving, from the
base station, a random access response message in response to a
transmission of the second-type random access message, the random
access response message including an uplink grant and an identifier
associated with the UE.
22. The method of claim 1, wherein the UE uses a radio network
temporary identifier (RNTI) to receive a response message
associated with the two-step random access procedure or the
four-step random access procedure.
23. The method of claim 1, wherein the UE uses, while operating in
an idle mode or an inactive mode, a random access radio network
temporary identifier (RA-RNTI) to receive a response message
associated with the two-step random access procedure or the
four-step random access procedure.
24. The method of claim 1, wherein the UE uses a cell radio network
temporary identifier (C-RNTI) to receive a response message
associated with a two-step random access procedure while the UE is
operating in a connected mode.
25. The method of claim 1, wherein the fallback timer is a timer or
a counter.
26. An apparatus for wireless communication at a user equipment
(UE), comprising: a memory; and at least one processor coupled to
the memory and configured to: determine that a fallback timer
associated with a two-step random access procedure is configured
for the UE; generate a random access message based at least on the
determining, wherein the random access message is one of a
first-type random access message associated with a four-step random
access procedure and including a preamble or a second-type random
access message associated with the two-step random access procedure
and including the preamble and a payload; and perform a random
access attempt by transmitting, to a base station, the random
access message.
27. A method of wireless communication at a base station,
comprising: providing, to a User Equipment (UE), an indication that
configures a fallback timer associated with a two-step random
access procedure; and receiving, from the UE, a random access
message based at least in part on the indication, wherein the
random access message is one of either a first-type random access
message associated with a four-step random access procedure and
including a preamble or a second-type random access message
associated with the two-step random access procedure and including
the preamble and a payload.
28. The method of claim 27, wherein the received random access
message is the second-type random access message, and further
comprising: attempting to decode the payload of the second-type
random access message; and providing, in a random access response
message, an uplink grant and at least one of timing advancement
information, contention resolution information, or RRC connection
setup information in response to successfully decoding the
payload.
29. The method of claim 28, further comprising: providing, in the
random access response message, the uplink grant and information
indicating a failure to decode the payload of the second-type
random access message in response to unsuccessfully decoding the
payload; and receiving, from the UE, a third-type random access
message associated with the four-step random access procedure and
including the payload based at least in part on the information
indicating the failure to decode the payload.
30. An apparatus for wireless communication at a base station,
comprising: a memory; and at least one processor coupled to the
memory and configured to: provide, to a User Equipment (UE), an
indication that configures a fallback timer associated with a
two-step random access procedure; and receive, from the UE, a
random access message based at least in part on the indication,
wherein the random access message is one of either a first-type
random access message associated with a four-step random access
procedure and including a preamble or a second-type random access
message associated with the two-step random access procedure and
including the preamble and a payload.
Description
CROSS REFERENCE TO RELATED APPLICATION(S)
[0001] This application claims the benefit of International Patent
Application Serial No. PCT/CN2019/074028, entitled "RANDOM ACCESS
PROCEDURE BASED ON TWO-STEP RANDOM ACCESS CHANNEL PROCEDURE AND
FOUR-STEP RANDOM ACCESS CHANNEL PROCEDURE" and filed on Jan. 30,
2019, which is expressly incorporated by reference herein in its
entirety.
BACKGROUND
Technical Field
[0002] The present disclosure relates generally to communication
systems, and more particularly, to a wireless communication system
to perform a random access channel procedure.
Introduction
[0003] Wireless communication systems are widely deployed to
provide various telecommunication services such as telephony,
video, data, messaging, and broadcasts. Typical wireless
communication systems may employ multiple-access technologies
capable of supporting communication with multiple users by sharing
available system resources. Examples of such multiple-access
technologies include code division multiple access (CDMA) systems,
time division multiple access (TDMA) systems, frequency division
multiple access (FDMA) systems, orthogonal frequency division
multiple access (OFDMA) systems, single-carrier frequency division
multiple access (SC-FDMA) systems, and time division synchronous
code division multiple access (TD-SCDMA) systems.
[0004] These multiple access technologies have been adopted in
various telecommunication standards to provide a common protocol
that enables different wireless devices to communicate on a
municipal, national, regional, and even global level. An example
telecommunication standard is 5G New Radio (NR). 5G NR is part of a
continuous mobile broadband evolution promulgated by Third
Generation Partnership Project (3GPP) to meet new requirements
associated with latency, reliability, security, scalability (e.g.,
with Internet of Things (IoT)), and other requirements. 5G NR
includes services associated with enhanced mobile broadband (eMBB),
massive machine type communications (mMTC), and ultra reliable low
latency communications (URLLC). Some aspects of 5G NR may be based
on the 4G Long Term Evolution (LTE) standard. There exists a need
for further improvements in 5G NR technology. These improvements
may also be applicable to other multi-access technologies and the
telecommunication standards that employ these technologies.
SUMMARY
[0005] The following presents a simplified summary of one or more
aspects in order to provide a basic understanding of such aspects.
This summary is not an extensive overview of all contemplated
aspects, and is intended to neither identify key or critical
elements of all aspects nor delineate the scope of any or all
aspects. Its sole purpose is to present some concepts of one or
more aspects in a simplified form as a prelude to the more detailed
description that is presented later.
[0006] A four-step random access channel (RACH) procedure is a type
of random access procedure in which a user equipment (UE) sends an
initial message that includes a preamble (referred to herein as
"msg1"). A two-step RACH procedure is a type of random access
procedure in which the UE sends an initial message that includes a
preamble and a payload (referred to herein as a "msgA"). However,
including the payload in the initial message associated with the
two-step RACH procedure (msgA) results in a relatively larger
initial message compared to the initial message associated with the
four-step RACH procedure (msg1). As a result, the inclusion of the
payload in the initial message associated with the two-step RACH
procedure (msgA) may reduce link budget and/or cell coverage.
[0007] The present disclosure provides unique techniques for
determining whether to perform a two-step RACH procedure or a
four-step RACH procedure when a random access procedure is
triggered. For example, the UE may perform one or more downlink
measurements to measure channel quality, such as reference signal
received power (RSRP) and/or a path loss measurement. Based on the
one or more downlink measurements, the UE may determine whether to
perform a two-step RACH procedure or to perform a four-step RACH
procedure. Additional or alternative aspects include determining
whether (or when) to revert to a four-step RACH procedure after
initiating a two-step RACH procedure. For example, while performing
a two-step RACH procedure, the UE may determine to stop performing
the two-step RACH procedure and to initiate a four-step RACH
procedure. In additional or alternative aspects, the UE may
transition from performing the two-step RACH procedure to
performing the four-step RACH procedure.
[0008] In an aspect of the disclosure, a method, a
computer-readable medium, and an apparatus are provided for
facilitating wireless communication at a UE. An example apparatus
determines that a fallback timer associated with a two-step random
access procedure is configured for the UE. The example apparatus
also generates a random access message based at least on the
determining. The random access message may be one of a first-type
random access message associated with a four-step random access
procedure and including a preamble or a second-type random access
message associated with the two-step random access procedure and
including the preamble and a payload. Further, the example
apparatus performs a random access attempt by transmitting, to a
base station, the random access message.
[0009] In another aspect of the disclosure, a method, a
computer-readable medium, and an apparatus are provided for
facilitating wireless communication at a UE. An example apparatus
determines whether to perform a two-step random access procedure or
a four-step random access procedure based at least on a fallback
timer associated with the two-step random access procedure not
being configured. The example apparatus also generates a random
access message based on the determining. The random access message
may be one of a first-type random access message associated with a
four-step random access procedure and including a preamble or a
second-type random access message associated with the two-step
random access procedure and including the preamble and a payload.
Additionally, the example apparatus performs a random access
attempt by transmitting, to a base station, the random access
message.
[0010] In another aspect of the disclosure, a method, a
computer-readable medium, and an apparatus are provided for
facilitating wireless communication at a base station. An example
apparatus provides, to a User Equipment (UE), an indication that
configures a fallback timer associated with a two-step random
access procedure. The example apparatus also receives, from the UE,
a random access message based at least in part on the indication.
The random access message may be one of either a first-type random
access message associated with a four-step random access procedure
and including a preamble or a second-type random access message
associated with the two-step random access procedure and including
the preamble and a payload.
[0011] In another aspect of the disclosure, a method, a
computer-readable medium, and an apparatus are provided for
facilitating wireless communication at a base station. An example
apparatus provides, to a UE, an indication of whether the base
station supports a two-step random access procedure. The example
apparatus also receives, from the UE, a random access message based
at least in part on the indication. The random access message may
be one of either a first-type random access message associated with
a four-step random access procedure and including a preamble or a
second-type random access message associated with the two-step
random access procedure and including the preamble and a
payload.
[0012] To the accomplishment of the foregoing and related ends, the
one or more aspects comprise the features hereinafter fully
described and particularly pointed out in the claims. The following
description and the annexed drawings set forth in detail certain
illustrative features of the one or more aspects. These features
are indicative, however, of but a few of the various ways in which
the principles of various aspects may be employed, and this
description is intended to include all such aspects and their
equivalents.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a diagram illustrating an example of a wireless
communications system and an access network.
[0014] FIGS. 2A, 2B, 2C, and 2D are diagrams illustrating examples
of a first 5G/NR frame, DL channels within a 5G/NR subframe, a
second 5G/NR frame, and UL channels within a 5G/NR subframe,
respectively.
[0015] FIG. 3 is a diagram illustrating an example of a base
station and user equipment (UE) in an access network.
[0016] FIG. 4 is a diagram illustrating a call flow diagram between
a UE and a base station implementing a four-step random access
channel (RACH) procedure.
[0017] FIG. 5 is a diagram illustrating a call flow diagram between
a UE and a base station implementing a two-step RACH procedure.
[0018] FIG. 6 is a diagram illustrating a call flow diagram between
a UE and a base station when the UE employs techniques for
determining whether to perform a two-step RACH procedure or a
four-step RACH procedure, as disclosed herein.
[0019] FIG. 7 is a flowchart of a method of wireless communication
for a UE to perform a random access procedure.
[0020] FIG. 8 is a flowchart of a method of wireless communication
for a UE to perform a random access procedure.
[0021] FIG. 9 is a conceptual data flow diagram illustrating the
data flow between different means/components in an example
apparatus.
[0022] FIG. 10 is a diagram illustrating an example of a hardware
implementation for an apparatus employing a processing system.
[0023] FIG. 11 is a flowchart of a method of wireless communication
for a base station to perform a random access procedure.
[0024] FIG. 12 is a flowchart of a method of wireless communication
for a base station to perform a random access procedure.
[0025] FIG. 13 is a conceptual data flow diagram illustrating the
data flow between different means/components in an example
apparatus.
[0026] FIG. 14 is a diagram illustrating an example of a hardware
implementation for an apparatus employing a processing system.
DETAILED DESCRIPTION
[0027] The detailed description set forth below in connection with
the appended drawings is intended as a description of various
configurations and is not intended to represent the only
configurations in which the concepts described herein may be
practiced. The detailed description includes specific details for
the purpose of providing a thorough understanding of various
concepts. However, it will be apparent to those skilled in the art
that these concepts may be practiced without these specific
details. In some instances, well known structures and components
are shown in block diagram form in order to avoid obscuring such
concepts.
[0028] Several aspects of telecommunication systems will now be
presented with reference to various apparatus and methods. These
apparatus and methods will be described in the following detailed
description and illustrated in the accompanying drawings by various
blocks, components, circuits, processes, algorithms, etc.
(collectively referred to as "elements"). These elements may be
implemented using electronic hardware, computer software, or any
combination thereof. Whether such elements are implemented as
hardware or software depends upon the particular application and
design constraints imposed on the overall system.
[0029] By way of example, an element, or any portion of an element,
or any combination of elements may be implemented as a "processing
system" that includes one or more processors. Examples of
processors include microprocessors, microcontrollers, graphics
processing units (GPUs), central processing units (CPUs),
application processors, digital signal processors (DSPs), reduced
instruction set computing (RISC) processors, systems on a chip
(SoC), baseband processors, field programmable gate arrays (FPGAs),
programmable logic devices (PLDs), state machines, gated logic,
discrete hardware circuits, and other suitable hardware configured
to perform the various functionality described throughout this
disclosure. One or more processors in the processing system may
execute software. Software shall be construed broadly to mean
instructions, instruction sets, code, code segments, program code,
programs, subprograms, software components, applications, software
applications, software packages, routines, subroutines, objects,
executables, threads of execution, procedures, functions, etc.,
whether referred to as software, firmware, middleware, microcode,
hardware description language, or otherwise.
[0030] Accordingly, in one or more example embodiments, the
functions described may be implemented in hardware, software, or
any combination thereof. If implemented in software, the functions
may be stored on or encoded as one or more instructions or code on
a computer-readable medium. Computer-readable media includes
computer storage media. Storage media may be any available media
that can be accessed by a computer. By way of example, and not
limitation, such computer-readable media can comprise a
random-access memory (RAM), a read-only memory (ROM), an
electrically erasable programmable ROM (EEPROM), optical disk
storage, magnetic disk storage, other magnetic storage devices,
combinations of the aforementioned types of computer-readable
media, or any other medium that can be used to store computer
executable code in the form of instructions or data structures that
can be accessed by a computer.
[0031] FIG. 1 is a diagram illustrating an example of a wireless
communications system and an access network 100. The wireless
communications system (also referred to as a wireless wide area
network (WWAN)) includes base stations 102, UEs 104, an Evolved
Packet Core (EPC) 160, and another core network 190 (e.g., a 5G
Core (5GC)). The base stations 102 may include macrocells (high
power cellular base station) and/or small cells (low power cellular
base station). The macrocells include base stations. The small
cells include femtocells, picocells, and microcells.
[0032] The base stations 102 configured for 4G LTE (collectively
referred to as Evolved Universal Mobile Telecommunications System
(UMTS) Terrestrial Radio Access Network (E-UTRAN)) may interface
with the EPC 160 through first backhaul links 132 (e.g., S1
interface). The base stations 102 configured for 5G NR
(collectively referred to as Next Generation RAN (NG-RAN)) may
interface with core network 190 through second backhaul links 184.
In addition to other functions, the base stations 102 may perform
one or more of the following functions: transfer of user data,
radio channel ciphering and deciphering, integrity protection,
header compression, mobility control functions (e.g., handover,
dual connectivity), inter-cell interference coordination,
connection setup and release, load balancing, distribution for
non-access stratum (NAS) messages, NAS node selection,
synchronization, radio access network (RAN) sharing, multimedia
broadcast multicast service (MBMS), subscriber and equipment trace,
RAN information management (RIM), paging, positioning, and delivery
of warning messages. The base stations 102 may communicate directly
or indirectly (e.g., through the EPC 160 or core network 190) with
each other over third backhaul links 134 (e.g., X2 interface). The
third backhaul links 134 may be wired or wireless.
[0033] The base stations 102 may wirelessly communicate with the
UEs 104. Each of the base stations 102 may provide communication
coverage for a respective geographic coverage area 110. There may
be overlapping geographic coverage areas 110. For example, the
small cell 102' may have a coverage area 110' that overlaps the
coverage area 110 of one or more macro base stations 102. A network
that includes both small cell and macrocells may be known as a
heterogeneous network. A heterogeneous network may also include
Home Evolved Node Bs (eNBs) (HeNBs), which may provide service to a
restricted group known as a closed subscriber group (CSG). The
communication links 120 between the base stations 102 and the UEs
104 may include uplink (UL) (also referred to as reverse link)
transmissions from a UE 104 to a base station 102 and/or downlink
(DL) (also referred to as forward link) transmissions from a base
station 102 to a UE 104. The communication links 120 may use
multiple-input and multiple-output (MIMO) antenna technology,
including spatial multiplexing, beamforming, and/or transmit
diversity. The communication links may be through one or more
carriers. The base stations 102/UEs 104 may use spectrum up to Y
MHz (e.g., 5, 10, 15, 20, 100, 400, etc. MHz) bandwidth per carrier
allocated in a carrier aggregation of up to a total of Yx MHz (x
component carriers) used for transmission in each direction. The
carriers may or may not be adjacent to each other. Allocation of
carriers may be asymmetric with respect to DL and UL (e.g., more or
fewer carriers may be allocated for DL than for UL). The component
carriers may include a primary component carrier and one or more
secondary component carriers. A primary component carrier may be
referred to as a primary cell (PCell) and a secondary component
carrier may be referred to as a secondary cell (SCell).
[0034] Certain UEs 104 may communicate with each other using
device-to-device (D2D) communication link 158. The D2D
communication link 158 may use the DL/UL WWAN spectrum. The D2D
communication link 158 may use one or more sidelink channels, such
as a physical sidelink broadcast channel (PSBCH), a physical
sidelink discovery channel (PSDCH), a physical sidelink shared
channel (PSSCH), and a physical sidelink control channel (PSCCH).
D2D communication may be through a variety of wireless D2D
communications systems, such as for example, FlashLinQ, WiMedia,
Bluetooth, ZigBee, Wi-Fi based on the IEEE 802.11 standard, LTE, or
NR.
[0035] The wireless communications system may further include a
Wi-Fi access point (AP) 150 in communication with Wi-Fi stations
(STAs) 152 via communication links 154 in a 5 GHz unlicensed
frequency spectrum. When communicating in an unlicensed frequency
spectrum, the STAs 152/AP 150 may perform a clear channel
assessment (CCA) prior to communicating in order to determine
whether the channel is available.
[0036] The small cell 102' may operate in a licensed and/or an
unlicensed frequency spectrum. When operating in an unlicensed
frequency spectrum, the small cell 102' may employ NR and use the
same 5 GHz unlicensed frequency spectrum as used by the Wi-Fi AP
150. The small cell 102', employing NR in an unlicensed frequency
spectrum, may boost coverage to and/or increase capacity of the
access network.
[0037] A base station 102, whether a small cell 102' or a macrocell
(e.g., a macro base station), may include and/or be referred to as
an eNB, gNodeB (gNB), or another type of base station. Some base
stations 180, such as a gNB, may operate in a traditional sub 6 GHz
spectrum, in millimeter wave (mmW) frequencies, and/or near mmW
frequencies in communication with the UE 104. When the gNB operates
in mmW or near mmW frequencies, the gNB may be referred to as an
mmW base station. Extremely high frequency (EHF) is part of the RF
in the electromagnetic spectrum. EHF has a range of 30 GHz to 300
GHz and a wavelength between 1 millimeter and 10 millimeters. Radio
waves in the band may be referred to as a millimeter wave. Near mmW
may extend down to a frequency of 3 GHz with a wavelength of 100
millimeters. The super high frequency (SHF) band extends between 3
GHz and 30 GHz, also referred to as centimeter wave. Communications
using the mmW/near mmW radio frequency band (e.g., 3 GHz-300 GHz)
has extremely high path loss and a short range. The mmW base
station, e.g., base station 180, may utilize beamforming 182 with
the UE 104 to compensate for the extremely high path loss and short
range. The base station 180 and the UE 104 may each include a
plurality of antennas, such as antenna elements, antenna panels,
and/or antenna arrays to facilitate the beamforming.
[0038] The base station 180 may transmit a beamformed signal to the
UE 104 in one or more transmit directions 182'. The UE 104 may
receive the beamformed signal from the base station 180 in one or
more receive directions 182''. The UE 104 may also transmit a
beamformed signal to the base station 180 in one or more transmit
directions. The base station 180 may receive the beamformed signal
from the UE 104 in one or more receive directions. The base station
180/UE 104 may perform beam training to determine the best receive
and transmit directions for each of the base station 180/ UE 104.
The transmit and receive directions for the base station 180 may or
may not be the same. The transmit and receive directions for the UE
104 may or may not be the same.
[0039] The EPC 160 may include a Mobility Management Entity (MME)
162, other MMEs 164, a Serving Gateway 166, a Multimedia Broadcast
Multicast Service (MBMS) Gateway 168, a Broadcast Multicast Service
Center (BM-SC) 170, and a Packet Data Network (PDN) Gateway 172.
The MME 162 may be in communication with a Home Subscriber Server
(HSS) 174. The MME 162 is the control node that processes the
signaling between the UEs 104 and the EPC 160. Generally, the MME
162 provides bearer and connection management. All user Internet
protocol (IP) packets are transferred through the Serving Gateway
166, which itself is connected to the PDN Gateway 172. The PDN
Gateway 172 provides UE IP address allocation as well as other
functions. The PDN Gateway 172 and the BM-SC 170 are connected to
the IP Services 176. The IP Services 176 may include the Internet,
an intranet, an IP Multimedia Subsystem (IMS), a PS Streaming
Service, and/or other IP services. The BM-SC 170 may provide
functions for MBMS user service provisioning and delivery. The
BM-SC 170 may serve as an entry point for content provider MBMS
transmission, may be used to authorize and initiate MBMS Bearer
Services within a public land mobile network (PLMN), and may be
used to schedule MBMS transmissions. The MBMS Gateway 168 may be
used to distribute MBMS traffic to the base stations 102 belonging
to a Multicast Broadcast Single Frequency Network (MBSFN) area
broadcasting a particular service, and may be responsible for
session management (start/stop) and for collecting eMBMS related
charging information.
[0040] The core network 190 may include a Access and Mobility
Management Function (AMF) 192, other AMFs 193, a Session Management
Function (SMF) 194, and a User Plane Function (UPF) 195. The AMF
192 may be in communication with a Unified Data Management (UDM)
196. The AMF 192 is the control node that processes the signaling
between the UEs 104 and the core network 190. Generally, the AMF
192 provides QoS flow and session management. All user Internet
protocol (IP) packets are transferred through the UPF 195. The UPF
195 provides UE IP address allocation as well as other functions.
The UPF 195 is connected to the IP Services 197. The IP Services
197 may include the Internet, an intranet, an IP Multimedia
Subsystem (IMS), a PS Streaming Service, and/or other IP
services.
[0041] The base station may include and/or be referred to as a gNB,
Node B, eNB, an access point, a base transceiver station, a radio
base station, a radio transceiver, a transceiver function, a basic
service set (BSS), an extended service set (ES S), a transmit
reception point (TRP), or some other suitable terminology. The base
station 102 provides an access point to the EPC 160 or core network
190 for a UE 104. Examples of UEs 104 include a cellular phone, a
smart phone, a session initiation protocol (SIP) phone, a laptop, a
personal digital assistant (PDA), a satellite radio, a global
positioning system, a multimedia device, a video device, a digital
audio player (e.g., MP3 player), a camera, a game console, a
tablet, a smart device, a wearable device, a vehicle, an electric
meter, a gas pump, a large or small kitchen appliance, a healthcare
device, an implant, a sensor/actuator, a display, or any other
similar functioning device. Some of the UEs 104 may be referred to
as IoT devices (e.g., parking meter, gas pump, toaster, vehicles,
heart monitor, etc.). The UE 104 may also be referred to as a
station, a mobile station, a subscriber station, a mobile unit, a
subscriber unit, a wireless unit, a remote unit, a mobile device, a
wireless device, a wireless communications device, a remote device,
a mobile subscriber station, an access terminal, a mobile terminal,
a wireless terminal, a remote terminal, a handset, a user agent, a
mobile client, a client, or some other suitable terminology.
[0042] Referring again to FIG. 1, in certain aspects, the UE 104
may be configured to manage one or more aspects of wireless
communication via a random access procedure. For example, the UE
104 of FIG. 1 includes a UE random access channel procedure
component 198 configured to determine that a fallback timer
associated with a two-step random access procedure is configured
for the UE. The example UE random access channel procedure
component 198 may also be configured to generate a random access
message based at least on the determining. The random access
message may be one of a first-type random access message associated
with a four-step random access procedure and including a preamble
or a second-type random access message associated with the two-step
random access procedure and including the preamble and a payload.
Further, the example UE random access channel procedure component
198 may be configured to perform a random access attempt by
transmitting, to a base station, the random access message.
[0043] In another example, the UE random access channel procedure
component 198 may be configured to determine whether to perform a
two-step random access procedure or a four-step random access
procedure based at least on a fallback timer associated with the
two-step random access procedure not being configured. The example
UE random access channel procedure component 198 may also be
configured to generate a random access message based on the
determining. The random access message may be one of a first-type
random access message associated with a four-step random access
procedure and including a preamble or a second-type random access
message associated with the two-step random access procedure and
including the preamble and a payload. Additionally, the example UE
random access channel procedure component 198 may be configured to
perform a random access attempt by transmitting, to a base station,
the random access message.
[0044] Referring still to FIG. 1, in certain aspects, the base
station 102/180 may be configured to manage one or more aspects of
wireless communication via a random access procedure. For example,
the base station 102/180 of FIG. 1 includes a base station random
access channel procedure component 199 configured to provide, to a
User Equipment (UE), an indication that configures a fallback timer
associated with a two-step random access procedure. The example
base station random access channel procedure component 199 may also
be configured to receive, from the UE, a random access message
based at least in part on the indication. The random access message
may be one of either a first-type random access message associated
with a four-step random access procedure and including a preamble
or a second-type random access message associated with the two-step
random access procedure and including the preamble and a
payload.
[0045] In another example, the base station random access channel
procedure component 199 may be configured to provide, to a UE, an
indication of whether the base station supports a two-step random
access procedure. The example base station random access channel
procedure component 199 may also be configured to receive, from the
UE, a random access message based at least in part on the
indication. The random access message may be one of either a
first-type random access message associated with a four-step random
access procedure and including a preamble or a second-type random
access message associated with the two-step random access procedure
and including the preamble and a payload.
[0046] Although the following description may be focused on 5GNR,
the concepts described herein may be applicable to other similar
areas, such as LTE, LTE-A, CDMA, GSM, and other wireless
technologies.
[0047] FIG. 2A is a diagram 200 illustrating an example of a first
subframe within a 5G/NR frame structure. FIG. 2B is a diagram 230
illustrating an example of DL channels within a 5G/NR subframe.
FIG. 2C is a diagram 250 illustrating an example of a second
subframe within a 5G/NR frame structure. FIG. 2D is a diagram 280
illustrating an example of UL channels within a 5G/NR subframe. The
5G/NR frame structure may be FDD in which for a particular set of
subcarriers (carrier system bandwidth), subframes within the set of
subcarriers are dedicated for either DL or UL, or may be TDD in
which for a particular set of subcarriers (carrier system
bandwidth), subframes within the set of subcarriers are dedicated
for both DL and UL. In the examples provided by FIGS. 2A, 2C, the
5G/NR frame structure is assumed to be TDD, with subframe 4 being
configured with slot format 28 (with mostly DL), where D is DL, U
is UL, and X is flexible for use between DL/UL, and subframe 3
being configured with slot format 34 (with mostly UL). While
subframes 3, 4 are shown with slot formats 34, 28, respectively,
any particular subframe may be configured with any of the various
available slot formats 0-61. Slot formats 0, 1 are all DL, UL,
respectively. Other slot formats 2-61 include a mix of DL, UL, and
flexible symbols. UEs are configured with the slot format
(dynamically through DL control information (DCI), or
semi-statically/statically through radio resource control (RRC)
signaling) through a received slot format indicator (SFI). Note
that the description infra applies also to a 5G/NR frame structure
that is TDD.
[0048] Other wireless communication technologies may have a
different frame structure and/or different channels. A frame (10
ms) may be divided into 10 equally sized subframes (1 ms). Each
subframe may include one or more time slots. Subframes may also
include mini-slots, which may include 7, 4, or 2 symbols. Each slot
may include 7 or 14 symbols, depending on the slot configuration.
For slot configuration 0, each slot may include 14 symbols, and for
slot configuration 1, each slot may include 7 symbols. The symbols
on DL may be cyclic prefix (CP) OFDM (CP-OFDM) symbols. The symbols
on UL may be CP-OFDM symbols (for high throughput scenarios) or
discrete Fourier transform (DFT) spread OFDM (DFT-s-OFDM) symbols
(also referred to as single carrier frequency-division multiple
access (SC-FDMA) symbols) (for power limited scenarios; limited to
a single stream transmission). The number of slots within a
subframe is based on the slot configuration and the numerology. For
slot configuration 0, different numerologies 0 to 5 allow for 1, 2,
4, 8, 16, and 32 slots, respectively, per subframe. For slot
configuration 1, different numerologies 0 to 2 allow for 2, 4, and
8 slots, respectively, per subframe. Accordingly, for slot
configuration 0 and numerology .mu., there are 14 symbols/slot and
2.sup..mu. slots/subframe. The subcarrier spacing and symbol
length/duration are a function of the numerology. The subcarrier
spacing may be equal to 2.sup..mu.*15 kHz, where .mu. is the
numerology 0 to 5. As such, the numerology .mu.=0 has a subcarrier
spacing of 15 kHz and the numerology .mu.=5 has a subcarrier
spacing of 480 kHz. The symbol length/duration is inversely related
to the subcarrier spacing. FIGS. 2A-2D provide an example of slot
configuration 0 with 14 symbols per slot and numerology .mu.=2 with
4 slots per subframe. The slot duration is 0.25 ms, the subcarrier
spacing is 60 kHz, and the symbol duration is approximately 16.67
.mu.s.
[0049] A resource grid may be used to represent the frame
structure. Each time slot includes a resource block (RB) (also
referred to as physical RBs (PRBs)) that extends 12 consecutive
subcarriers. The resource grid is divided into multiple resource
elements (REs). The number of bits carried by each RE depends on
the modulation scheme.
[0050] As illustrated in FIG. 2A, some of the REs carry reference
(pilot) signals (RS) for the UE. The RS may include demodulation RS
(DM-RS) (indicated as R.sub.x for one particular configuration,
where 100.times. is the port number, but other DM-RS configurations
are possible) and channel state information reference signals
(CSI-RS) for channel estimation at the UE. The RS may also include
beam measurement RS (BRS), beam refinement RS (BRRS), and phase
tracking RS (PT-RS).
[0051] FIG. 2B illustrates an example of various DL channels within
a subframe of a frame. The physical downlink control channel
(PDCCH) carries DCI within one or more control channel elements
(CCEs), each CCE including nine RE groups (REGs), each REG
including four consecutive REs in an OFDM symbol. A primary
synchronization signal (PSS) may be within symbol 2 of particular
subframes of a frame. The PSS is used by a UE 104 to determine
subframe/symbol timing and a physical layer identity. A secondary
synchronization signal (SSS) may be within symbol 4 of particular
subframes of a frame. The SSS is used by a UE to determine a
physical layer cell identity group number and radio frame timing.
Based on the physical layer identity and the physical layer cell
identity group number, the UE can determine a physical cell
identifier (PCI). Based on the PCI, the UE can determine the
locations of the aforementioned DM-RS. The physical broadcast
channel (PBCH), which carries a master information block (MIB), may
be logically grouped with the PSS and SSS to form a synchronization
signal (SS)/PBCH block. The MIB provides a number of RBs in the
system bandwidth and a system frame number (SFN). The physical
downlink shared channel (PDSCH) carries user data, broadcast system
information not transmitted through the PBCH such as system
information blocks (SIBs), and paging messages.
[0052] As illustrated in FIG. 2C, some of the REs carry DM-RS
(indicated as R for one particular configuration, but other DM-RS
configurations are possible) for channel estimation at the base
station. The UE may transmit DM-RS for the physical uplink control
channel (PUCCH) and DM-RS for the physical uplink shared channel
(PUSCH). The PUSCH DM-RS may be transmitted in the first one or two
symbols of the PUSCH. The PUCCH DM-RS may be transmitted in
different configurations depending on whether short or long PUCCHs
are transmitted and depending on the particular PUCCH format used.
The UE may transmit sounding reference signals (SRS). The SRS may
be transmitted in the last symbol of a subframe. The SRS may have a
comb structure, and a UE may transmit SRS on one of the combs. The
SRS may be used by a base station for channel quality estimation to
enable frequency-dependent scheduling on the UL.
[0053] FIG. 2D illustrates an example of various UL channels within
a subframe of a frame. The PUCCH may be located as indicated in one
configuration. The PUCCH carries uplink control information (UCI),
such as scheduling requests, a channel quality indicator (CQI), a
precoding matrix indicator (PMI), a rank indicator (RI), and HARQ
ACK/NACK feedback. The PUSCH carries data, and may additionally be
used to carry a buffer status report (BSR), a power headroom report
(PHR), and/or UCI.
[0054] FIG. 3 is a block diagram of a base station 310 in
communication with a UE 350 in an access network. In the DL, IP
packets from the EPC 160 may be provided to a controller/processor
375. The controller/processor 375 implements layer 3 and layer 2
functionality. Layer 3 includes a radio resource control (RRC)
layer, and layer 2 includes a service data adaptation protocol
(SDAP) layer, a packet data convergence protocol (PDCP) layer, a
radio link control (RLC) layer, and a medium access control (MAC)
layer. The controller/processor 375 provides RRC layer
functionality associated with broadcasting of system information
(e.g., MIB, SIBs), RRC connection control (e.g., RRC connection
paging, RRC connection establishment, RRC connection modification,
and RRC connection release), inter radio access technology (RAT)
mobility, and measurement configuration for UE measurement
reporting; PDCP layer functionality associated with header
compression/ decompression, security (ciphering, deciphering,
integrity protection, integrity verification), and handover support
functions; RLC layer functionality associated with the transfer of
upper layer packet data units (PDUs), error correction through ARQ,
concatenation, segmentation, and reassembly of RLC service data
units (SDUs), re-segmentation of RLC data PDUs, and reordering of
RLC data PDUs; and MAC layer functionality associated with mapping
between logical channels and transport channels, multiplexing of
MAC SDUs onto transport blocks (TBs), demultiplexing of MAC SDUs
from TBs, scheduling information reporting, error correction
through HARQ, priority handling, and logical channel
prioritization.
[0055] The transmit (TX) processor 316 and the receive (RX)
processor 370 implement layer 1 functionality associated with
various signal processing functions. Layer 1, which includes a
physical (PHY) layer, may include error detection on the transport
channels, forward error correction (FEC) coding/decoding of the
transport channels, interleaving, rate matching, mapping onto
physical channels, modulation/demodulation of physical channels,
and MIMO antenna processing. The TX processor 316 handles mapping
to signal constellations based on various modulation schemes (e.g.,
binary phase-shift keying (BPSK), quadrature phase-shift keying
(QPSK), M-phase-shift keying (M-PSK), M-quadrature amplitude
modulation (M-QAM)). The coded and modulated symbols may then be
split into parallel streams. Each stream may then be mapped to an
OFDM subcarrier, multiplexed with a reference signal (e.g., pilot)
in the time and/or frequency domain, and then combined together
using an Inverse Fast Fourier Transform (IFFT) to produce a
physical channel carrying a time domain OFDM symbol stream. The
OFDM stream is spatially precoded to produce multiple spatial
streams. Channel estimates from a channel estimator 374 may be used
to determine the coding and modulation scheme, as well as for
spatial processing. The channel estimate may be derived from a
reference signal and/or channel condition feedback transmitted by
the UE 350. Each spatial stream may then be provided to a different
antenna 320 via a separate transmitter 318TX. Each transmitter
318TX may modulate an RF carrier with a respective spatial stream
for transmission.
[0056] At the UE 350, each receiver 354RX receives a signal through
its respective antenna 352. Each receiver 354RX recovers
information modulated onto an RF carrier and provides the
information to the receive (RX) processor 356. The TX processor 368
and the RX processor 356 implement layer 1 functionality associated
with various signal processing functions. The RX processor 356 may
perform spatial processing on the information to recover any
spatial streams destined for the UE 350. If multiple spatial
streams are destined for the UE 350, they may be combined by the RX
processor 356 into a single OFDM symbol stream. The RX processor
356 then converts the OFDM symbol stream from the time-domain to
the frequency domain using a Fast Fourier Transform (FFT). The
frequency domain signal comprises a separate OFDM symbol stream for
each subcarrier of the OFDM signal. The symbols on each subcarrier,
and the reference signal, are recovered and demodulated by
determining the most likely signal constellation points transmitted
by the base station 310. These soft decisions may be based on
channel estimates computed by the channel estimator 358. The soft
decisions are then decoded and deinterleaved to recover the data
and control signals that were originally transmitted by the base
station 310 on the physical channel. The data and control signals
are then provided to the controller/processor 359, which implements
layer 3 and layer 2 functionality.
[0057] The controller/processor 359 can be associated with a memory
360 that stores program codes and data. The memory 360 may be
referred to as a computer-readable medium. In the UL, the
controller/processor 359 provides demultiplexing between transport
and logical channels, packet reassembly, deciphering, header
decompression, and control signal processing to recover IP packets
from the EPC 160. The controller/processor 359 is also responsible
for error detection using an ACK and/or NACK protocol to support
HARQ operations.
[0058] Similar to the functionality described in connection with
the DL transmission by the base station 310, the
controller/processor 359 provides RRC layer functionality
associated with system information (e.g., MIB, SIBs) acquisition,
RRC connections, and measurement reporting; PDCP layer
functionality associated with header compression/decompression, and
security (ciphering, deciphering, integrity protection, integrity
verification); RLC layer functionality associated with the transfer
of upper layer PDUs, error correction through ARQ, concatenation,
segmentation, and reassembly of RLC SDUs, re-segmentation of RLC
data PDUs, and reordering of RLC data PDUs; and MAC layer
functionality associated with mapping between logical channels and
transport channels, multiplexing of MAC SDUs onto TBs,
demultiplexing of MAC SDUs from TBs, scheduling information
reporting, error correction through HARQ, priority handling, and
logical channel prioritization.
[0059] Channel estimates derived by a channel estimator 358 from a
reference signal or feedback transmitted by the base station 310
may be used by the TX processor 368 to select the appropriate
coding and modulation schemes, and to facilitate spatial
processing. The spatial streams generated by the TX processor 368
may be provided to different antenna 352 via separate transmitters
354TX. Each transmitter 354TX may modulate an RF carrier with a
respective spatial stream for transmission.
[0060] The UL transmission is processed at the base station 310 in
a manner similar to that described in connection with the receiver
function at the UE 350. Each receiver 318RX receives a signal
through its respective antenna 320. Each receiver 318RX recovers
information modulated onto an RF carrier and provides the
information to a RX processor 370.
[0061] The controller/processor 375 can be associated with a memory
376 that stores program codes and data. The memory 376 may be
referred to as a computer-readable medium. In the UL, the
controller/processor 375 provides demultiplexing between transport
and logical channels, packet reassembly, deciphering, header
decompression, control signal processing to recover IP packets from
the UE 350. IP packets from the controller/processor 375 may be
provided to the EPC 160. The controller/processor 375 is also
responsible for error detection using an ACK and/or NACK protocol
to support HARQ operations.
[0062] At least one of the TX processor 368, the RX processor 356,
and the controller/processor 359 may be configured to perform
aspects in connection with the UE random access channel procedure
component 198 of FIG. 1.
[0063] At least one of the TX processor 316, the RX processor 370,
and the controller/processor 375 may be configured to perform
aspects in connection with the base station random access channel
procedure component 199 of FIG. 1.
[0064] A wireless communication system may include a base station
and a UE. The base station may provide a cell on which the UE may
operate. In order to communicate in the wireless communication
system, the base station and the UE may acquire a timing advance
for uplink signals. The base station and the UE may acquire timing
synchronization (e.g., uplink timing synchronization) through a
random access procedure. For example, the UE may initiate the
random access procedure for initial access to the cell provided by
the base station, RRC connection reestablishment, handover from
another base station to the base station, reacquisition of timing
synchronization, transition from an RRC Inactive state, SCell
timing alignment, request for Other System Information (SI), and/or
beam failure recovery.
[0065] In certain aspects, the random access procedure may be a
four-step random access channel (RACH) procedure in which the UE
and the base station exchange four messages. In certain aspects,
the random access procedure may be a two-step RACH procedure in
which the UE and the base station exchange two messages.
[0066] FIG. 4 is a diagram illustrating a call flow diagram 400
between a UE 402 and a base station 404 implementing a four-step
RACH procedure 410. Aspects of the UE 402 may be described with
respect to the UE 104 of FIG. 1 and/or the UE 350 of FIG. 3.
Aspects of the base station 404 may be described with respect to
the base station 102 of FIG. 1, the base station 180 of FIG. 1,
and/or the base station 310 of FIG. 3.
[0067] In the illustrated example of FIG. 4, the four-step RACH
procedure 410 includes the exchange of four messages. Specifically,
the UE 402 may initiate the message exchange of the four-step RACH
procedure 410 by sending, to the base station 404, a first
four-step RACH message 412 including a preamble (e.g., without a
payload). The base station 404 then sends, to the UE 402, a second
four-step RACH message 414 including a random access response
(RAR). In certain aspects, the second four-step RACH message 414
may include an identifier of the RACH preamble, a timing advance
(TA), an uplink grant for the UE 402 to transmit data, cell radio
network temporary identifier (C-RNTI), and/or a back-off indicator.
The UE 402 then sends a third four-step RACH message 416 to the
base station 404. In certain aspects, the third four-step RACH
message 416 may include a radio resource control (RRC) connection
request, an RRC connection re-establishment request, or an RRC
connection resume request, depending on the trigger for the UE 402
initiating the random access procedure. The base station 404 then
completes the four-step RACH procedure 410 by sending a fourth
four-step RACH message 418 to the UE 402. In certain aspects, the
fourth four-step RACH message 418 includes timing advancement
information, contention resolution information, and/or RRC
connection setup information. As shown in FIG. 4, the first
four-step RACH message 412 may be referred to as "msg1," the second
four-step RACH message 414 may be referred to as "msg2," the third
four-step RACH message 416 may be referred to as "msg3," and the
fourth four-step RACH message 418 may be referred to as "msg4."
[0068] Although not shown, in some examples, the UE 402 may
re-transmit a RACH message. For example, in certain aspects, after
transmitting the msg1 412, the UE 402 may re-transmit (e.g.,
periodically, a-periodically, and/or as a one-time event) the msg1
412 until the msg2 414 is received from the base station 404 and/or
a timer expires. In other examples, the RACH message received by
the UE 402 (e.g., the msg2 414 and/or the msg4 418) may indicate
that the base station 404 was unable to process (e.g., decode) at
least a portion of a RACH message transmitted by the UE 402. In
some such examples, the UE 402 may then re-transmit the
corresponding RACH message.
[0069] FIG. 5 is a diagram illustrating a call flow diagram 500
between a UE 502 and a base station 504 implementing a two-step
RACH procedure 510. Aspects of the UE 502 may be described with
respect to the UE 104 of FIG. 1, the UE 350 of FIG. 3, and/or the
UE 402 of FIG. 4. Aspects of the base station 504 may be described
with respect to the base station 102 of FIG. 1, the base station
180 of FIG. 1, the base station 310 of FIG. 3, and/or the base
station 404 of FIG. 4.
[0070] In the illustrated example of FIG. 5, the two-step RACH
procedure 510 includes the exchange of two messages. Specifically,
the UE 502 may initiate the message exchange of the two-step RACH
procedure 510 by sending a first two-step RACH message 512 to the
base station 504 and, responsive to the first two-step RACH message
512, the base station 504 may complete the message exchange of the
two-step RACH procedure 510 by sending a second two-step RACH
message 514 to the UE 502. In certain aspects, the first two-step
RACH message 512 may be referred to as "msgA" and the second
two-step RACH message 514 may be referred to as "msgB."
[0071] In certain aspects, to initiate the two-step RACH procedure
510, the UE 502 may generate the msgA 512. For the two-step RACH
procedure 510, the UE 502 may generate the msgA 512 to include at
least a preamble 512a (e.g., a PRACH preamble) and a payload 512b.
In certain aspects, the preamble 512a may correspond to the msg1
412 and the payload 512b may correspond to the msg3 416 of the
four-step RACH procedure 410 of FIG. 4.
[0072] The UE 502 may be identified by the base station 504
according to an identifier (ID) of the UE 502, such as a radio
network temporary identifier (RNTI) (e.g., a random access (RA)
RNTI, a temporary RNTI, etc.). The msgA 512 may be the first
transmission by the UE 502 to the base station 504 and, therefore,
the base station 504 may benefit from a mechanism for indicating
the ID of the UE 502 to the base station 504 in the msgA 512,
particularly because the msgA 512 may include data from the UE 502
in the payload 512b. Accordingly, the UE 502 may indicate an ID of
the UE 502 using one or more (or a combination of) approaches for
including information in the msgA 512.
[0073] In response to receiving the msgA 512, the base station 504
may generate the msgB 514. The base station 504 may generate the
msgB 514 to include control information in a PDCCH and data in a
PDSCH. The base station 504 may send the msgB 514 to the UE 502 to
complete the two-step RACH procedure 510. In certain aspects,
information included in the msgB 514 may correspond to the msg2 414
and the msg4 418 of the four-step RACH procedure 410 of FIG. 4. The
UE 502 may receive the msgB 514, and the UE 502 may acquire timing
synchronization based on the msgB 514.
[0074] Although not shown, in certain aspects, the UE 502 may
re-transmit a RACH message. For example, in certain aspects, after
transmitting the msgA 512, the UE 502 may re-transmit (e.g.,
periodically, a-periodically, and/or as a one-time event) the msgA
512 until the msgB 514 is received from the base station 504 and/or
a timer expires. In some examples, the RACH response message
received by the UE 502 (e.g., the msgB 514) may indicate that the
base station 504 was unable to process (e.g., decode) at least a
portion of the RACH message. In some such examples, the UE 502 may
then re-transmit the corresponding RACH message. For example, the
base station 504 may transmit a RACH message indicating that the
base station 504 was unable to decode the payload 512b of the msgA
512 and the UE 502 may retransmit the msgA 512.
[0075] While the two-step RACH procedure 510 of FIG. 5 differs in
some aspects from the four-step RACH procedure 410 of FIG. 4, some
aspects may be common across the RACH procedures 410, 510. For
example, sequences associated with a physical RACH (PRACH) and
sequences associated with DMRS used for the four-step RACH
procedure 410 may also be used for the two-step RACH procedure 510.
Further, a TX chain used for a PUSCH in the four-step RACH
procedure 410 may also be used for the two-step RACH procedure
510.
[0076] While performing a two-step RACH procedure includes
exchanging fewer messages than when performing a four-step RACH
procedure, the increased size of the first two-step RACH message
(e.g., the msgA 512 of FIG. 5) compared to the size of the first
four-step RACH message (e.g., the msg1 412 of FIG. 4) may reduce
link budget and, thus, may adversely impact cell coverage. Thus,
techniques disclosed herein enable the UE to determine whether to
perform a two-step RACH procedure or a four-step RACH procedure. In
certain aspects, the UE may additionally or alternatively determine
when to terminate performing the two-step RACH procedure and to
initiate performing the four-step RACH procedure. In certain
aspects, the UE may additionally or alternatively determine when to
transition from performing the two-step RACH procedure to the
four-step RACH procedure.
[0077] FIG. 6 is a diagram illustrating a call flow diagram 600
between a UE 602 and a base station 604 when the UE 602 employs
techniques for determining whether to perform a two-step RACH
procedure or a four-step RACH procedure, as disclosed herein.
Aspects of the UE 602 may be described with respect to the UE 104
of FIG. 1, the UE 350 of FIG. 3, the UE 402 of FIG. 4, and/or the
UE 502 of FIG. 5. Aspects of the base station 604 may be described
with respect to the base station 102 of FIG. 1, the base station
180 of FIG. 1, the base station 310 of FIG. 3, the base station 404
of FIG. 4, and/or the base station 504 of FIG. 5.
[0078] The base station 604 may periodically send (e.g., broadcast)
information associated with operating on the cell provided by the
base station 604. As described with respect to FIG. 2B, supra, the
base station 604 may send a MIB and one or more SIBs. In the
illustrated example of FIG. 6, the base station 604 transmits
configuration information 610 associated with performing a RACH
procedure. In certain aspects, the base station 604 may transmit
the configuration information 610 via system information while the
UE 602 is operating in a connected mode, operating in an idle mode,
or operating in an inactive mode. In certain aspects, the base
station 604 may transmit the configuration information 610 via
dedicated signaling while the UE 602 is operating in a connected
mode.
[0079] In some aspects, the configuration information 610 may
indicate whether the base station 604 supports performing a
two-step RACH procedure. In some aspects, the configuration
information 610 may indicate that the base station 604 supports the
two-step RACH procedure for one or more UE access classes. In some
aspects, the configuration information 610 may include one or more
parameter(s) associated with performing the two-step RACH
procedure. For example, the configuration information 610 may
include one or more of a payload size, a Reference Signal Received
Power (RSRP) threshold, a path loss threshold, a fallback timer
setting, a first-type random access message transmittal count
threshold, and/or a second-type random access message transmittal
count threshold.
[0080] In certain aspects, the payload size parameter may be
associated with, for example, the payload 512b of FIG. 5. In
certain aspects, the payload size parameter may include a set of
payload sizes. In certain such examples, each payload size included
in the set of payload sizes may correspond to a set of one or more
preambles. In certain examples, the set of one or more preambles
may be disjointed preambles. In certain aspects, the Reference
Signal Received Power (RSRP) threshold may be associated with a
minimum RSRP measurement at which the UE 602 may perform the
two-step RACH procedure. In certain aspects, the path loss
threshold may be associated with a maximum path loss measurement at
which the UE 602 may perform the two-step RACH procedure. In
certain aspects, the fallback timer setting may indicate whether
the UE 602 is configured to enable a fallback timer while
performing a two-step RACH procedure. In certain aspects, the
first-type random access message transmittal count threshold is
associated with a maximum quantity of first-type random access
message transmittals that the UE 602 may perform. As disclosed
herein, a first-type random access message is a random access
message that includes a preamble (e.g., the msg1 412 of the
four-step RACH procedure 410 of FIG. 4) without a payload. Thus,
the first-type random access message transmittal count threshold
indicates a maximum quantity of transmissions and/or
re-transmissions of the msg1 412 that the UE 602 may perform. In
some examples, the second-type random access message transmittal
count threshold is associated with a maximum quantity of
second-type random access message transmittals that the UE 602 may
perform. As disclosed herein, a second-type random access message
may be a random access message that includes a preamble and a
payload (e.g., the msgA 512 of the two-step RACH procedure 510 of
FIG. 5). Thus, the second-type random access message transmittal
count threshold indicates a maximum quantity of transmissions
and/or re-transmissions of the msgA 512 that the UE 602 may
perform.
[0081] The UE 602 may receive and decode the configuration
information 610 and may subsequently perform a RACH attempt based
at least in part on the configuration information 610. For example,
at 612, the UE 602 determines whether to perform a two-step RACH
procedure (e.g., the two-step RACH procedure 510 of FIG. 5) or a
four-step RACH procedure (e.g., the four-step RACH procedure 410 of
FIG. 4) based at least in part on the configuration information
610, including the one or more parameters. For example, if the
configuration information 610 indicates that the base station 604
does not support the two-step RACH procedure, then the UE 602
determines, at 612, to perform the four-step RACH procedure. In
certain aspects, the configuration information 610 may indicate
that the base station 604 supports the two-step RACH procedure for
one or more UE access classes. In certain such examples, if an
access class associated with the UE 602 is not indicated as
supported by the configuration information 610, the UE 602
determines, at 612, to perform the four-step RACH procedure.
[0082] However, if the configuration information 610 indicates that
the base station 604 supports the two-step RACH procedure (and/or
if the access class associated with the UE is indicated as being
supported by the base station 604 for performing the two-step RACH
procedure), then the UE 602 may perform a second check to determine
whether an estimated link quality between the UE 602 and the base
station 604 is satisfactory to perform the two-step RACH procedure.
As described above, due to the larger size of the msgA compared to
the size of the msg1 (e.g., when the msgA includes a preamble and a
payload compared to the msg1 that includes a preamble without a
payload), an increased link budget is needed to perform the
two-step RACH procedure compared to performing the four-step RACH
procedure. To that end, in certain aspects, after determining that
the base station 604 supports the two-step RACH procedure (and/or
the base station 604 supports the two-step RACH procedure for the
access class associated with the UE 602), the UE 602 may perform
one or more downlink measurements to measure channel quality, such
as reference signal received power (RSRP) and/or a path loss
measurement. For example, the UE 602 may measure a reference signal
and compare the reference signal measurement to an associated
parameter and/or threshold provided in the configuration
information 610. In certain aspects, the reference signal may be
comprised in a Synchronization Signal Block (SSB). In certain
aspects, the reference signal may comprise a channel state
information reference signal (CSI-RS). In some examples, the UE 602
may select the reference signal based on a predetermined rule. For
example, the UE 602 may select the reference signal for which an
RSRP measurement is available. In some examples, the UE 602 may
select the reference signal from among a plurality of reference
signals received by the UE 602 and based on respective reference
signal measurements. For example, the UE 602 may select the
reference signal associated with the highest RSRP measurement, the
lowest path loss measurement, etc.
[0083] In some examples, after selecting the reference signal and
measuring the selected reference signal, the UE 602 may compare the
reference signal measurement to a threshold associated with the
reference signal measurement. In some examples, the threshold
associated with the reference signal measurement may be provided by
the base station 604 via the configuration information 610 (e.g.,
one or more parameter(s)). Based on the comparison (e.g., whether
the reference signal measurement satisfies the associated
threshold), the UE 602 may determine whether to perform the
two-step RACH procedure or the four-step RACH procedure.
[0084] For example, if the reference signal measurement is an RSRP
measurement, the UE 602 may compare the RSRP measurement of the
reference signal to the RSRP threshold provided in the
configuration information 610. In some such examples, if the UE 602
determines that the RSRP measurement of the reference signal
satisfies the RSRP threshold (e.g., the RSRP measurement of the
reference signal is greater than or equal to the RSRP threshold),
the UE 602 may determine, at 612, to perform the two-step RACH
procedure. Otherwise, if the UE 602 determines that the RSRP
measurement of the reference signal does not satisfy the RSRP
threshold (e.g., the RSRP measurement of the reference signal is
less than the RSRP threshold), the UE 602 may determine, at 612, to
perform the four-step RACH procedure.
[0085] In some examples, the reference signal measurement is a path
loss measurement and the UE 602 may compare the path loss
measurement of the reference signal to the path loss threshold
provided in the configuration information 610. In some such
examples, if the UE 602 determines that the path loss measurement
of the reference signal satisfies the path loss threshold (e.g.,
the path loss measurement of the reference signal is less than or
equal to the path loss threshold), the UE 602 may determine, at
612, to perform the two-step RACH procedure. Otherwise, if the UE
602 determines that the path loss measurement of the reference
signal does not satisfy the path loss threshold (e.g., the path
loss measurement of the reference signal is greater than the path
loss threshold), the UE 602 may determine, at 612, to perform the
four-step RACH procedure.
[0086] At 614, the UE 602 generates a random access message 616
based on the determined RACH procedure (e.g., at 612). For example,
after determining to perform the four-step RACH procedure, the UE
602 may generate a first random access message including a preamble
without a payload (e.g., the msg1 412). Otherwise, if the UE 602
determines to perform the two-step RACH procedure, the UE 602 may
generate a second random access message including a preamble and a
payload (e.g., the msgA 512 including the preamble 512a and the
payload 512b). The UE 602 then attempts to perform the determined
RACH procedure by transmitting the generated random access message
616 to the base station 604.
[0087] In some examples, after transmitting the generated random
access message 616 to the base station 604, the UE 602 increments a
transmittal count associated with the random access message 616.
For example, if the random access message 616 is the msg1 412
including a preamble without a payload, the UE 602 increments a
first-type random access message transmittal count that corresponds
to the quantity of transmissions and/or re-transmissions of the
first-type random access message (e.g., the msg1 412). Otherwise,
if the random access message 616 is the msgA 512 including the
preamble 512a and the payload 512b, the UE 602 increments a
second-type random access message transmittal count that
corresponds to the quantity of transmissions and/or
re-transmissions of the second-type random access message (e.g.,
the msgA 512).
[0088] At 618, the base station 604 generates a random access
response message 620 based at least in part on the random access
message 616 received from the UE 602. For example, if the random
access message 616 is the msg1 412 including the preamble without a
payload, the base station 604 may determine that the UE 602 is
performing the four-step RACH procedure and may generate the msg2
414 (e.g., of the four-step RACH procedure 410 of FIG. 4)
including, for example, an identifier of the RACH preamble, a time
advance (TA), an uplink grant for the UE 602 to transmit data, cell
radio network temporary identifier (C-RNTI), and/or a back-off
indicator. Otherwise, if the random access message 616 is the msgA
512 including the preamble 512a and the payload 512b, the base
station 604 may determine that the UE 602 is performing the
two-step RACH procedure and may generate the msgB 514 (e.g., of the
two-step RACH procedure 510 of FIG. 5) including, for example, an
uplink grant for the UE 602 to transmit data, control information
in a PDCCH, and/or data in a PDSCH. The base station 604 may then
transmit the random access response message 620 (e.g., the msg2 414
or the msgB 514) to the UE 602.
[0089] In some examples, the UE 602 may use RNTI to receive a
response message associated with the two-step RACH procedure (e.g.,
the msgB 514) or to receive a response message associated with the
four-step RACH procedure (e.g., the msg2 414). In some examples,
the UE may use, while operating in an idle mode or an inactive
mode, a random access RNTI (RA-RNTI) to receive a response message
associated with the two-step RACH procedure (e.g., the msgB 514) or
to receive a response message associated with the four-step RACH
procedure (e.g., the msg2 414). In some examples, the UE 602 may
use a cell RNTI (C-RNTI) to receive a response message associated
with a two-step RACH procedure while the UE is operating in a
connected mode.
[0090] In some examples, the UE 602 may detect a re-transmission
triggering event. In some examples, a re-transmission triggering
event may include not receiving a response message from the base
station in response to the random access message (e.g., no msg2 414
or msgB 514 is received by the UE 602). In some examples, a
re-transmission triggering event may include receiving a response
message including information indicating a failure by the base
station 604 to process (e.g., decode) at least a portion of the
random access message received by the base station 604 (e.g., the
payload 512b of the msgA 512).
[0091] In some examples, in response to detecting a re-transmission
triggering event, the UE 602 may re-transmit the random access
message. In some examples, in response to detecting a
re-transmission triggering event, the UE 602 may determine to stop
the current RACH procedure and initiate a new RACH procedure. In
some examples, in response to detecting a re-transmission
triggering event, the UE 602 may determine to transition from the
current RACH procedure to another RACH procedure. In some examples,
in response to detecting a re-transmission triggering event, the UE
602 may stop performing all RACH procedures (until the UE 602 is
able to next perform the one or more downlink measurements).
[0092] In some examples, after detecting a re-transmission
triggering event, the UE 602 may determine how to proceed based on
the current RACH procedure being performed and/or based on one or
more parameters included in the configuration information 610. For
example, in some examples, the one or more parameters may include
the fallback timer setting indicative of whether a fallback timer
is configured for the UE 602 and/or on a random access message
transmittal count threshold.
[0093] In some examples, the fallback timer setting may indicate
that a fallback timer is not configured for the UE 602. In some
such examples, the UE 602 may determine that the UE 602 has not
received a response message (e.g., the random access response
message 620). The UE 602 may then determine how to proceed based on
a transmittal count associated with the random access message. For
example, when performing the two-step RACH procedure, the UE 602
may compare the msgA transmittal count (e.g., the second-type
random access message transmittal count) to the msgA transmittal
count threshold (e.g., the second-type random access message
transmittal count threshold provided via the configuration
information 610).
[0094] Otherwise, if the UE 602 is performing the four-step RACH
procedure, the UE 602 may compare the msg1 transmittal count (e.g.,
the first-type random access message transmittal count) to the msg1
transmittal count threshold (e.g., the first-type random access
message transmittal count threshold provided via the configuration
information 610). In some examples, if the UE 602 determines that
the random access message transmittal count does not satisfy the
respective random access message transmittal count threshold (e.g.,
the msgA transmittal count is greater than the msgA transmittal
count threshold or the msg1 transmittal count is greater than the
msg1 transmittal count threshold), the UE 602 stops performing RACH
procedures and notifies the upper layer (e.g., the PHY layer).
Otherwise, if the UE 602 determines that the random access message
transmittal count satisfies the respective random access message
transmittal count threshold (e.g., the msgA transmittal count is
less than or equal to the msgA transmittal count threshold or the
msg1 transmittal count is less than or equal to the msg1
transmittal count threshold), the UE 602 may return to 612 to
determine whether to perform the two-step RACH procedure or the
four-step RACH procedure (e.g., based on whether a reference signal
measurement satisfies a threshold associated with the reference
signal measurement).
[0095] In some examples, if the fallback timer setting indicates
that the fallback timer is configured and active for the UE 602,
the UE 602 may default to attempting to perform the two-step RACH
procedure. For example, while the fallback timer is active, the UE
602 may repeat transmissions of the msgA for reference signals with
reference signal measurements that satisfy the associated threshold
until the UE 602 receives a msgB (e.g., the two-step RACH procedure
was successfully completed), the fallback timer expires, or the
msgA transmittal count does not satisfy the msgA transmittal count
threshold (e.g., the second-type random access message transmittal
count is greater than the second-type random access message
transmittal count threshold). In some examples, if the UE 602
determines that the fallback timer expired or the msgA transmittal
count does not satisfy the msgA transmittal count threshold, the UE
602 may stop performing the two-step RACH procedure and initiate
performing the four-step RACH procedure (e.g., the UE may transmit
the msg1 412 of the four-step RACH procedure 410 including the
preamble without a payload).
[0096] The fallback timer may be implemented by any suitable
technique for providing an upper-bound limiting when the two-step
RACH attempts that the UE 602 may perform. In some examples, the
fallback timer may be a timer that provides a duration during which
the UE 602 may initiate performing the two-step RACH procedure. In
some such examples, if the UE 602 determines that the fallback
timer is active, the UE 602 may continue performing two-step RACH
attempts. However, if the UE 602 determines that the fallback timer
is not active, then the UE 602 may stop performing two-step RACH
attempts and may start performing four-step RACH attempts.
[0097] In some examples, the fallback timer may be a counter that
provides a maximum quantity of two-step RACH attempts that the UE
602 may perform. For example, the UE 602 may increment a count each
time the UE 602 performs a two-step RACH attempt. In some such
examples, if the UE 602 determines that the counter is active
(e.g., the quantity of two-step RACH attempts performed by the UE
602 is less than the maximum quantity of two-step RACH attempts),
then the UE may perform another two-step RACH attempt. However, if
the UE 602 determines that the counter is not active (e.g., the
quantity of two-step RACH attempts performed by the UE 602 is equal
to the maximum quantity of two-step RACH attempts), then the UE may
stop performing two-step RACH attempts and may start performing
four-step RACH attempts.
[0098] Parameters associated with the fallback timer may be
included in the configuration information 610. For example, if the
fallback timer is a timer, then the configuration information 610
may indicate a duration during which the UE 602 may perform
two-step RACH attempts. In other examples in which the fallback
timer is a counter, then the configuration information 610 may
indicate the maximum quantity of two-step RACH attempts that the UE
602 may perform. In some examples, the parameters associated with
the fallback timer may be a network-wide parameter provided via a
SIB. In some examples, the parameters associated with the fallback
timer may be provided via dedicated signaling. In some examples,
the parameters associated with the fallback timer may indicate
whether the respective fallback timer (e.g., the timer or the
counter) is active or not active.
[0099] In some examples, the UE 602 may transition from performing
the two-step RACH procedure to the four-step RACH procedure based
on, for example, the response message received from the base
station 604. For example, the base station 604 may receive the msgA
512 including the preamble 512a and the payload 512b from the UE
602. While processing the msgA 512, the base station 604 may
successfully decode the preamble 512a of the msgA 512 but fail to
decode the payload 512b of the msgA 512. In some examples, the
payload 512b may include an identifier associated with the UE 604.
The base station 604 may then send a response message that is the
same as the second four-step RACH response message 414 (e.g., the
msg2). In some examples, the msg2 414 may include an uplink grant
for the UE 602. In some such examples, in response to receiving the
msg2 414 from the base station 604, the UE 602 may transmit the
third four-step RACH message 416 (e.g., the msg3) to the base
station 604 using the uplink grant and may wait for the fourth
four-step RACH response message 418 (e.g., the msg4) from the base
station 604. In some such examples, the RACH attempt is successful
if the UE 602 is able to decode the msg4 418 and the msg4 418
includes the UE identifier of the UE 602. However, if the UE 602 is
unable to decode the msg4 418 and/or the msg4 418 does not include
the UE identifier of the UE 602, the RACH attempt may be considered
as unsuccessful. In some such examples, the UE 602 may then return
to 612 to determine whether to perform a two-step RACH procedure or
a four-step RACH procedure.
[0100] FIG. 7 is a flowchart 700 of a method of wireless
communication. The method may be performed by a UE (e.g., the UE
104 of FIG. 1, the UE 350 of FIG. 3, the UE 402 of FIG. 4, the UE
502 of FIG. 5, the UE 602 of FIG. 6, the UE 1350 of FIG. 13, the
apparatus 902/902' of FIGS. 9 and 10, respectively, and/or the
processing system 1014, which may include the memory 360 and which
may be the entire UE 350 or a component of the UE 350, such as the
TX processor 368, the RX processor 356, and/or the
controller/processor 359). One or more of the illustrated
operations may be omitted, transposed, or contemporaneous. In FIG.
7, optional aspects are illustrated with a dashed line. The method
provides for improved communication between a UE and a network and
enables a UE to determine when to perform a two-step RACH procedure
attempt and when to perform a four-step RACH procedure attempt when
a fallback timer is configured. Thus, aspects may improve the
efficiency of the UE accessing the network for data
transmissions.
[0101] At 702, the UE may receive configuration information
associated with a RACH procedure, as described in connection with
the configuration information 610 of FIG. 6. The receiving of the
configuration information may be performed, for example, by a
reception component 904 of the apparatus 902 of FIG. 9. For
example, the configuration information may indicate whether the
network supports a two-step RACH procedure and, if the two-step
RACH procedure is supported, whether a fallback time is configured
for the UE. In some examples, the configuration information may
indicate one or more UE access classes for which the network
supports the two-step RACH procedure. The configuration information
may additionally or alternatively include one or more parameter(s)
associated with the two-step RACH procedure, such as a payload size
(and/or a set of payload sizes), a Reference Signal Received Power
(RSRP) threshold, a path loss threshold, a fallback timer setting
(e.g., a duration or a maximum quantity), a first-type random
access message transmittal count threshold (e.g., a msg1
transmittal count threshold), and/or a second-type random access
message transmittal count threshold (e.g., a msgA transmittal count
threshold). In some examples, the UE may receive the configuration
information, including the one or more parameter(s), via system
information while the UE is operating in a connected mode,
operating in an idle mode, or operating in an inactive mode. In
some examples, the UE may receive the configuration information,
including the one or more parameter(s), via dedicated signaling
while the UE is operating in a connected mode.
[0102] At 704, the UE determines that a fallback timer associated
with a two-step random access procedure is configured for the UE,
as described in connection with 612 of FIG. 6. The determining that
the fallback timer is configured for the UE may be performed, for
example, by a fallback timer component 930 of the apparatus 902.
For example, the UE may determine that the fallback timer is
configured based on the one or more parameter(s) included in the
configuration information. In some examples, the fallback timer may
be a timer. In some examples, the fallback timer may be a
counter.
[0103] At 706, the UE may measure a reference signal, as described
in connection with 612 of FIG. 6. The measuring of the reference
signal may be performed by, for example, a measurement component
918 of the apparatus 902. In some examples, the reference signal
may be comprised in a Synchronization Signal Block (SSB). In some
examples, the reference signal may comprise a channel state
information reference signal (CSI-RS). In some examples, the UE may
select the reference signal to measure based on a predetermined
rule. In some examples, the UE may select the reference signal to
measure from among a plurality of reference signals received by the
UE and based on respective reference signal measurements.
[0104] At 708, the UE may compare a measurement of the reference
signal to at least one parameter, as described in connection with
612 of FIG. 6. The comparing of the reference signal measurement to
the at least one parameter may be performed, for example, by a
comparison component 920 of the apparatus 902. In some examples,
the UE may compare the reference signal measurement to a threshold
associated with the at least one parameter. For example, if the
reference signal measurement is an RSRP measurement, the UE may
compare the RSPR measurement to the RSRP threshold included in the
configuration information. In some examples, if the reference
signal measurement is a path loss measurement, the UE may compare
the path loss measurement to the path loss threshold included in
the configuration.
[0105] At 710, the UE generates a random access message based at
least on the fallback timer being configured for the UE, as
described in connection with 614 of FIG. 6. The generating of the
random access message may be performed, for example, by a
generation component 910 of the apparatus 902. In some examples,
the UE may generate a first-type random access message associated
with a four-step random access procedure and including a preamble
without a payload (e.g., the msg1). In some examples, the UE may
generate a second-type random access message associated with the
two-step random access procedure and including the preamble and a
payload (e.g., the msgA).
[0106] In some examples, the generating of the random access
message is further based on at least one parameter of the
configuration information. For example, the UE may determine to
perform the two-step random access procedure and generate the
second-type random access message when the measurement of the
reference signal satisfies a threshold associated with the at least
one parameter (at 708). For example, when the measurement of the
reference signal comprises an RSRP of the reference signal, the UE
may determine to generate the second-type random access message
when the RSRP of the reference signal is greater than or equal to
the RSRP threshold. In some examples, when the measurement of the
reference signal comprises a path loss measurement associated with
the reference signal, the UE may determine to generate the
second-type random access message when the path loss measurement is
less than or equal to the path loss threshold. In some examples,
when the measurement of the reference signal does not satisfy the
threshold associated with the at least one parameter, then the UE
may determine to perform the four-step random access procedure and
generate the first-type random access message.
[0107] At 712, the UE performs a random access attempt by
transmitting the random access message, as described in connection
with the random access message 616 of FIG. 6. The transmitting of
the random access message may be performed, for example, by a
transmission component 906 of the apparatus 902.
[0108] At 714, the UE may increment a random access message
transmittal count associated with the random access message, as
described in connection with 616 of FIG. 6. The incrementing of the
random access message transmittal count associated with the random
access message may be performed, for example, by an increment
component 922 of the apparatus 902. For example, after transmitting
a second-type random access message (e.g., the msgA), the UE may
increment a second-type random access message transmittal count.
The UE may increment a first-type random access message transmittal
count after transmitting a first-type random access message (e.g.,
the msg1).
[0109] At 716, the UE may determine whether to repeat transmission
of the random access message, as described in connection with 612
and 620 of FIG. 6. The determining of whether to repeat
transmission of the random access message may be performed, for
example, by a count component 924 and a repeat component 926 of the
apparatus 902. In some examples, the UE may determine whether the
random access message transmittal count satisfies a respective
random access message transmittal count threshold if a response
message is not received from the base station. For example, the UE
may determine to repeat a transmission of the random access message
in response to detecting a re-transmission triggering event in
which the UE has not received a response message, for example, from
the base station. In some such examples, the UE may determine to
repeat the transmission of the random access message when the
respective random access message transmittal count satisfies the
corresponding random access message transmittal count threshold and
the fallback timer is configured (and active) for the UE. However,
if the UE determines that the fallback timer is not active and the
random access message transmit count does not satisfy the
corresponding random access message transmittal count threshold,
the UE may determine to terminate performing any RACH
procedures.
[0110] For example, if the random access message is a second-type
random access message, the UE may compare the second-type random
access message transmittal count to a second-type random access
message transmittal count threshold, and if the second-type random
access message count threshold is satisfied, the UE may determine
to repeat the transmission of the random access message (e.g. the
second-type random access message). In some examples, the
determining of whether to repeat transmission of the random access
message (e.g., the second-type random access message may also be
based on whether the fallback timer is active. For example, if the
UE determines that the fallback timer is configured and active,
then the UE may determine to repeat the transmission of the random
access message (e.g. the second-type random access message). In
some such examples, if the UE determines that the fallback timer is
not active and/or that the random access message count does not
satisfy the respective random access message transmittal count
threshold, then the UE may determine not to repeat transmission of
the random access message. For example, the UE may generate a
first-type random access message to transmit instead of repeating
transmission of the second-type random access message.
[0111] At 718, the UE may repeat transmission of the random access
message (e.g., the second-type random access message) or transmit a
new random access message (e.g., the first-type random access
message), as described in connection with 612 of FIG. 6. The
retransmission of the random access message or the transmission of
a new random access message may be performed, for example, by the
transmission component 906 of the apparatus 902.
[0112] At 720, the UE may receive a random access response message
from the base station, as described in connection with 620 of FIG.
6. The receiving of the random access response message may be
performed, for example, by the reception component 904 of the
apparatus 902. In some examples, the UE may use a RNTI to receive
the random access response message. In some examples, the UE may
use an RA-RNTI to receive the random access response message, for
example, while the UE is operating in an idle mode or an inactive
mode. In some examples, the UE may use a C-RNTI to receive the
random access response message, for example, while the UE is
operating in the connected mode.
[0113] In some examples in which the UE is performing the two-step
RACH procedure, the random access response message may include an
uplink grant and an identifier associated with the UE. In some such
examples, the UE may determine that the base station successfully
processed (e.g., decoded) the second-type random access message
(e.g., transmitted at 712 or retransmitted at 718).
[0114] However, in some examples, the random access response
message may include an uplink grant and information indicating a
failure to decode the payload of the second-type random access
message. In some such examples, the UE may transmit, at 722,
another random access message when the random access response
message indicates an unsuccessful decoding of the transmitted
random access message, as described in connection with 612 and 614
of FIG. 6. The transmitting of another random access message may be
performed, for example, by the transmission component 906 and the
RACH component 912 of the apparatus 902. In some examples, the UE
may transition to performing the four-step RACH procedure by
generating and transmitting a third-type random access message
including the payload (e.g., the msg3 416 of the four-step RACH
procedure 410).
[0115] FIG. 8 is a flowchart 800 of a method of wireless
communication. The method may be performed by a UE (e.g., the UE
104 of FIG. 1, the UE 350 of FIG. 3, the UE 402 of FIG. 4, the UE
502 of FIG. 5, the UE 602 of FIG. 6, the UE 1250 of FIG. 12, the
apparatus 902/902' of FIGS. 9 and 10, respectively, and/or the
processing system 1014, which may include the memory 360 and which
may be the entire UE 350 or a component of the UE 350, such as the
TX processor 368, the RX processor 356, and/or the
controller/processor 359). One or more of the illustrated
operations may be omitted, transposed, or contemporaneous. In FIG.
8, optional aspects are illustrated with a dashed line. The method
provides for improved communication between a UE and a network and
enables a UE to determine when to perform a two-step RACH procedure
attempt and when to perform a four-step RACH procedure attempt when
a fallback timer is not configured. Thus, aspects may improve the
efficiency of the UE accessing the network for data
transmissions.
[0116] At 802, the UE may receive configuration information
associated with a RACH procedure, as described in connection with
the configuration information 610 of FIG. 6. The receiving of the
configuration information may be performed, for example, by a
reception component 904 of the apparatus 902 of FIG. 9. For
example, the configuration information may indicate whether the
network supports a two-step RACH procedure and, if the two-step
RACH procedure is supported, whether a fallback time is configured
for the UE. In some examples, the configuration information may
indicate one or more UE access classes for which the network
supports the two-step RACH procedure. The configuration information
may additionally or alternatively include one or more parameter(s)
associated with the two-step RACH procedure, such as a payload size
(and/or a set of payload sizes), a Reference Signal Received Power
(RSRP) threshold, a path loss threshold, a fallback timer setting
(e.g., a duration or a maximum quantity), a first-type random
access message transmittal count threshold (e.g., a msg1
transmittal count threshold), and/or a second-type random access
message transmittal count threshold (e.g., a msgA transmittal count
threshold). In some examples, the UE may receive the configuration
information, including the one or more parameter(s), via system
information while the UE is operating in a connected mode,
operating in an idle mode, or operating in an inactive mode. In
some examples, the UE may receive the configuration information,
including the one or more parameter(s), via dedicated signaling
while the UE is operating in a connected mode.
[0117] At 804, the UE may measure a reference signal, as described
in connection with 612 of FIG. 6. The measuring of the reference
signal may be performed by, for example, a measurement component
918 of the apparatus 902. In some examples, the reference signal
may be comprised in a Synchronization Signal Block (SSB). In some
examples, the reference signal may comprise a channel state
information reference signal (CSI-RS). In some examples, the UE may
select the reference signal to measure based on a predetermined
rule. In some examples, the UE may select the reference signal to
measure from among a plurality of reference signals received by the
UE and based on respective reference signal measurements.
[0118] At 806, the UE may compare a measurement of the reference
signal to at least one parameter, as described in connection with
612 of FIG. 6. The comparing of the reference signal measurement to
the at least one parameter may be performed, for example, by a
comparison component 920 of the apparatus 902. In some examples,
the UE may compare the reference signal measurement to a threshold
associated with the at least one parameter. For example, if the
reference signal measurement is an RSRP measurement, the UE may
compare the RSPR measurement to the RSRP threshold included in the
configuration information. In some examples, if the reference
signal measurement is a path loss measurement, the UE may compare
the path loss measurement to the path loss threshold included in
the configuration.
[0119] At 808, the UE determines whether to perform a two-step RACH
procedure or a four-step RACH procedure based at least on a
fallback timer associated with the two-step RACH procedure not
being configured, as described in connection with 612 of FIG. 6.
The determining that the fallback timer is not configured for the
UE may be performed, for example, by a fallback timer component 930
of the apparatus 902. For example, the UE may determine that the
fallback timer is not configured based on the one or more
parameter(s) included in the configuration information.
[0120] In some examples, the determining of whether to perform the
two-step RACH procedure or the four-step RACH procedure may be
further based on at least one parameter of the configuration
information. For example, the UE may determine to perform the
two-step random access procedure when the measurement of the
reference signal satisfies a threshold associated with the at least
one parameter (at 806). For example, when the measurement of the
reference signal comprises an RSRP of the reference signal, the UE
may determine to perform the two-step RACH procedure when the RSRP
of the reference signal is greater than or equal to the RSRP
threshold. In some examples, when the measurement of the reference
signal comprises a path loss measurement associated with the
reference signal, the UE may determine to perform the two-step RACH
procedure when the path loss measurement is less than or equal to
the path loss threshold. In some examples, when the measurement of
the reference signal does not satisfy the threshold associated with
the at least one parameter, then the UE may determine to perform
the four-step random access procedure.
[0121] At 810, the UE generates a random access message, as
described in connection with 614 of FIG. 6. The generating of the
random access message may be performed, for example, by a
generation component 910 of the apparatus 902. In some examples,
the UE may generate a first-type random access message associated
with a four-step random access procedure and including a preamble
without a payload (e.g., the msg1). In some examples, the UE may
generate a second-type random access message associated with the
two-step random access procedure and including the preamble and a
payload (e.g., the msgA).
[0122] At 812, the UE performs a random access attempt by
transmitting the random access message, as described in connection
with the random access message 616 of FIG. 6. The transmitting of
the random access message may be performed, for example, by a
transmission component 906 of the apparatus 902.
[0123] At 814, the UE may increment a random access message
transmittal count associated with the random access message, as
described in connection with 616 of FIG. 6. The incrementing of the
random access message transmittal count associated with the random
access message may be performed, for example, by an increment
component 922 of the apparatus 902. For example, after transmitting
a second-type random access message (e.g., the msgA), the UE may
increment a second-type random access message transmittal count.
The UE may increment a first-type random access message transmittal
count after transmitting a first-type random access message (e.g.,
the msg1).
[0124] At 816, the UE may determine whether to repeat transmission
of the random access message, as described in connection with 612
and 620 of FIG. 6. The determining of whether to repeat
transmission of the random access message may be performed, for
example, by a count component 924 and a repeat component 926 of the
apparatus 902. In some examples, the UE may determine whether the
random access message transmittal count satisfies a respective
random access message transmittal count threshold if a response
message is not received from the base station. For example, the UE
may determine to repeat a transmission of the random access message
in response to detecting a re-transmission triggering event in
which the UE has not received a response message, for example, from
the base station. In some such examples, the UE may determine to
repeat the transmission of the random access message when the
respective random access message transmittal count satisfies the
corresponding random access message transmittal count threshold.
However, if the UE determines that the random access message
transmit count does not satisfy the corresponding random access
message transmittal count threshold, the UE may determine to
terminate performing any RACH procedures.
[0125] For example, if the random access message is a second-type
random access message, the UE may compare the second-type random
access message transmittal count to a second-type random access
message transmittal count threshold, and if the second-type random
access message count threshold is satisfied, the UE may determine
to repeat the transmission of the random access message (e.g. the
second-type random access message). In some examples, if the UE
determines that the random access message count does not satisfy
the respective random access message transmittal count threshold,
then the UE may determine not to repeat transmission of the random
access message. For example, the UE may generate a first-type
random access message to transmit instead of repeating transmission
of the second-type random access message.
[0126] At 818, the UE may repeat transmission of the random access
message (e.g., the second-type random access message) or transmit a
new random access message (e.g., the first-type random access
message), as described in connection with 612 of FIG. 6. The
retransmission of the random access message or the transmission of
a new random access message may be performed, for example, by the
transmission component 906 of the apparatus 902.
[0127] At 820, the UE may receive a random access response message
from the base station, as described in connection with 620 of FIG.
6. The receiving of the random access response message may be
performed, for example, by the reception component 904 of the
apparatus 902. In some examples, the UE may use a RNTI to receive
the random access response message. In some examples, the UE may
use an RA-RNTI to receive the random access response message, for
example, while the UE is operating in an idle mode or an inactive
mode. In some examples, the UE may use a C-RNTI to receive the
random access response message, for example, while the UE is
operating in the connected mode.
[0128] In some examples in which the UE is performing the two-step
RACH procedure, the random access response message may include an
uplink grant and an identifier associated with the UE. In some such
examples, the UE may determine that the base station successfully
processed (e.g., decoded) the second-type random access message
(e.g., transmitted at 812 or retransmitted at 818).
[0129] However, in some examples, the random access response
message may include an uplink grant and information indicating a
failure to decode the payload of the second-type random access
message. In some such examples, the UE may transmit, at 822,
another random access message when the random access response
message indicates an unsuccessful decoding of the transmitted
random access message, as described in connection with 612 and 614
of FIG. 6. The transmitting of another random access message may be
performed, for example, by the transmission component 906 and the
RACH component 912 of the apparatus 902. In some examples, the UE
may transition to performing the four-step RACH procedure by
generating and transmitting a third-type random access message
including the payload (e.g., the msg3 416 of the four-step RACH
procedure 410).
[0130] FIG. 9 is a conceptual data flow diagram 900 illustrating
the data flow between different means/components in an example
apparatus 902. The apparatus may be a UE. The apparatus 902 may
include a reception component 904 configured to receive downlink
communication from a base station 950 (e.g., as described in
connection with 702 and 802). The apparatus 902 may include a
transmission component 906 configured to transmit uplink
communication to the base station 950 (e.g., as described in
connection 712, 718, 722, 812, 818, and 822). The apparatus 902 may
include a determination component 908 configured to determine
whether to perform a two-step RACH procedure or to perform a
four-step RACH procedure (e.g., as described in connection 708 and
808). The apparatus 902 may include a generation component 910
configured to generate a random access message based on the
determination provided by the determination component 908 (e.g., as
described in connection with 710, 716, 722, 810, 816, and 822). In
some examples, the random access message may be a first-type random
access message including a preamble (e.g., the msg1) when the
determining is to perform the four-step RACH procedure or the
random access message may be a second-type random access message
including a preamble and a payload (e.g., the msgA) when the
determining is to perform the four-step RACH procedure. In some
examples, the random access message may be a third-type random
access message including a payload (e.g., the msg3) when a response
message from the base station indicates that the base station
unsuccessfully processed (e.g., decode) the payload of the
second-type random access message.
[0131] The apparatus 902 may include a RACH component 912
configured to perform a RACH attempt by transmitting, to a base
station, the random access message (e.g., as described in
connection with 712 and 812).
[0132] The apparatus 902 may include an indication component 914
configured to receive, from the base station, an indication that
indicates whether the base station supports a two-step RACH
procedure (e.g., as described in connection with 702 and 802). In
some examples, the determination component 908 may be configured to
determine whether to generate the first-type random access message
or the second-type random access message based on the
indication.
[0133] The apparatus 902 may include a parameter component 916
configured to receive, from the base station, at least one
parameter associated with the two-step RACH procedure (e.g., as
described in connection with 702 and 802). In some examples, the at
least one parameter may include one or more of a payload size
(and/or a set of payload sizes), a Reference Signal Received Power
(RSRP) threshold, a path loss threshold, a fallback timer setting,
a first-type random access message transmittal count threshold, or
a second-type random access message transmittal count threshold. In
some examples, the determination component 908 may be configured to
determine whether to generate the first random access message or
the second random access message based on the at least one
parameter.
[0134] The apparatus 902 may include a measurement component 918
configured to measure a reference signal and a comparison component
920 configured to compare a measurement of the reference signal to
the at least one parameter (e.g., as described in connection with
704/804 and 706/806, respectively). In some examples, the
determination component 908 may be configured to determine to
generate the second-type random access message when the measurement
of the reference signal satisfies a threshold associated with the
at least one parameter. In another example, the determination
component 908 may be configured to determine to generate the
first-type random access message when the measurement of the at
least one reference signal does not satisfy a threshold associated
with the at least one parameter.
[0135] In some examples, the random access message may be the
second-type random access message including a preamble and a
payload, and the apparatus 902 may include an increment component
922 configured to increment a second-type random access message
transmittal count after the transmitting of the second-type random
access message (e.g., as described in connection 714 and 814). The
apparatus 902 may include a count component 924 configured to
determine whether the second-type random access message transmittal
count satisfies a second-type random access message transmittal
count threshold if a response message is not received from the base
station and a repeat component 926 configured to determine whether
to repeat transmission of the second-type random access message or
to perform the four-step RACH procedure by generating the
first-type random access message based on whether the second-type
random access message transmittal count satisfies the second-type
random access message transmittal count threshold (e.g., as
described in connection with 716 and 816).
[0136] The apparatus 902 may include a response component 928
configured to receive, from the base station, a random access
response message in response to the transmission of the second-type
random access message including the preamble and the payload (e.g.,
as described in connection with 720 and 820). In some examples, the
random access response message may include an uplink grant and
information indicating a failure to decode the payload of the
second-type random access message. In some examples, the RACH
component 912 may be configured to transmit, to the base station, a
third-type random access message comprising the payload based on
the uplink grant, the third-type random access message associated
with the four-step RACH procedure. In some examples, the
determination component 908 may be configured to determine whether
to perform another RACH attempt using the two-step RACH procedure
or the four-step RACH procedure when no response to the third-type
random access message is received or when the UE receives a
response to the third-type random access message indicating another
failure to decode the payload.
[0137] The apparatus 902 may include a fallback timer component 930
configured to determine whether a fallback timer associated with
the two-step random access procedure is configured for the UE
(e.g., as describe in connection with 704).
[0138] The apparatus 902 may include additional components that
perform each of the blocks of the algorithms in the aforementioned
flowcharts of FIGS. 7 and/or 8. As such, each block in the
aforementioned flowcharts of FIGS. 7 and/or 8 may be performed by a
component and the apparatus may include one or more of those
components. The components may be one or more hardware components
specifically configured to carry out the stated
processes/algorithm, implemented by a processor configured to
perform the stated processes/algorithm, stored within a
computer-readable medium for implementation by a processor, or some
combination thereof.
[0139] FIG. 10 is a diagram 1000 illustrating an example of a
hardware implementation for an apparatus 902' employing a
processing system 1014. The processing system 1014 may be
implemented with a bus architecture, represented generally by the
bus 1024. The bus 1024 may include any number of interconnecting
buses and bridges depending on the specific application of the
processing system 1014 and the overall design constraints. The bus
1024 links together various circuits including one or more
processors and/or hardware components, represented by the processor
1004, the components 904, 906, 908, 910, 912, 914, 916, 918, 920,
922, 924, 926, 928, 930, and the computer-readable medium/memory
1006. The bus 1024 may also link various other circuits such as
timing sources, peripherals, voltage regulators, and power
management circuits, which are well known in the art, and
therefore, will not be described any further.
[0140] The processing system 1014 may be coupled to a transceiver
1010. The transceiver 1010 is coupled to one or more antennas 1020.
The transceiver 1010 provides a means for communicating with
various other apparatus over a transmission medium. The transceiver
1010 receives a signal from the one or more antennas 1020, extracts
information from the received signal, and provides the extracted
information to the processing system 1014, specifically the
reception component 904. In addition, the transceiver 1010 receives
information from the processing system 1014, specifically the
transmission component 906, and based on the received information,
generates a signal to be applied to the one or more antennas 1020.
The processing system 1014 includes a processor 1004 coupled to a
computer-readable medium/memory 1006. The processor 1004 is
responsible for general processing, including the execution of
software stored on the computer-readable medium/memory 1006. The
software, when executed by the processor 1004, causes the
processing system 1014 to perform the various functions described
supra for any particular apparatus. The computer-readable
medium/memory 1006 may also be used for storing data that is
manipulated by the processor 1004 when executing software. The
processing system 1014 further includes at least one of the
components 904, 906, 908, 910, 912, 914, 916, 918, 920, 922, 924,
926, 928, 930. The components may be software components running in
the processor 1004, resident/stored in the computer readable
medium/memory 1006, one or more hardware components coupled to the
processor 1004, or some combination thereof. The processing system
1014 may be a component of the UE 350 and may include the memory
360 and/or at least one of the TX processor 368, the RX processor
356, and the controller/processor 359. Alternatively, the
processing system 1014 may be the entire UE (e.g., see 350 of FIG.
3).
[0141] In one configuration, the apparatus 902/902' for wireless
communication includes means for determining that a fallback timer
associated with a two-step random access procedure is configured
for the UE. The apparatus 902/902' may also include means for
generating a random access message based at least on the
determining, where the random access message is one of a first-type
random access message associated with a four-step random access
procedure and including a preamble or a second-type random access
message associated with the two-step random access procedure and
including the preamble and a payload. The apparatus 902/902' may
also include means for performing a random access attempt by
transmitting, to a base station, the random access message. The
apparatus 902/902' may also include means for receiving, from the
base station, at least one parameter associated with the two-step
random access procedure, the at least one parameter including one
or more of a payload size, a set of payload sizes, a Reference
Signal Received Power (RSRP) threshold, a path loss threshold, a
fallback timer setting, a first-type random access message
transmittal count threshold, or a second-type random access message
transmittal count threshold. The apparatus 902/902' may also
include means for generating the random access message further
based on the at least one parameter. The apparatus 902/902' may
also include means for measuring a reference signal. The apparatus
902/902' may also include means for comparing a measurement of the
reference signal to the at least one parameter. The apparatus
902/902' may also include means for determining to generate the
second-type random access message when the measurement of the
reference signal satisfies a threshold associated with the at least
one parameter. The apparatus 902/902' may also include means for
selecting the reference signal to measure based on a predetermined
rule. The apparatus 902/902' may also include means for selecting
the reference signal to measure from among a plurality of reference
signals received by the UE and based on respective reference signal
measurements. The apparatus 902/902' may also include means for
determining to generate the second-type random access message when
the measurement of the reference signal comprises a Reference
Signal Received Power (RSRP) of the reference signal and the RSRP
of the reference signal is greater than or equal to the RSRP
threshold. The apparatus 902/902' may also include means for
determining to generate the second-type random access message when
the measurement of the reference signal comprises a path loss
measurement associated with the reference signal and the path loss
measurement is less than or equal to the path loss threshold. The
apparatus 902/902' may also include means for measuring at least
one reference signal. The apparatus 902/902' may also include means
for comparing a measurement of the at least one reference signal to
the at least one parameter. The apparatus 902/902' may also include
means for determining to generate the first-type random access
message when the measurement of the at least one reference signal
does not satisfy a threshold associated with the at least one
parameter. The apparatus 902/902' may also include means for
receiving, from the base station, an indication that indicates
whether the base station supports the two-step random access
procedure, wherein the fallback timer is configured when the base
station supports the two-step random access procedure. The
apparatus 902/902' may also include means for generating the random
access message further based on an access class associated with the
UE. The apparatus 902/902' may also include means for incrementing
a second-type random access message transmittal count after the
transmitting of the second-type random access message. The
apparatus 902/902' may also include means for determining whether
the second-type random access message transmittal count satisfies a
second-type random access message transmittal count threshold if a
response message is not received from the base station. The
apparatus 902/902' may also include means for determining whether
to repeat transmission of the second-type random access message or
to generate the first-type random access message based on whether
the second-type random access message transmittal count satisfies
the second-type random access message transmittal count threshold.
The apparatus 902/902' may also include means for determining
whether to repeat the transmission of the second-type random access
message or to perform the four-step random access procedure further
based on whether the fallback timer is active for the UE. The
apparatus 902/902' may also include means for generating the
first-type random access message when the second-type random access
message transmittal count does not satisfy the second-type random
access message transmittal count threshold. The apparatus 902/902'
may also include means for repeating the transmission of the
second-type random access message while the fallback timer is
active and if the second-type random access message transmittal
count is less than the second-type random access message
transmittal count threshold. The apparatus 902/902' may also
include means for receiving, from the base station, a random access
response message in response to the transmission of the second-type
random access message, the random access response message including
an uplink grant and information indicating a failure to decode the
payload of the second-type random access message. The apparatus
902/902' may also include means for transmitting, to the base
station, a third-type random access message comprising the payload
based on the uplink grant, the third-type random access message
associated with the four-step random access procedure. The
apparatus 902/902' may also include means for determining whether
to perform another random access attempt using the two-step random
access procedure or the four-step random access procedure when the
fallback timer is active and no response to the third-type random
access message is received or when the fallback timer is active and
a received response to the third-type random access message
indicates another failure to decode the payload. The apparatus
902/902' may also include means for receiving, from the base
station, a random access response message in response to the
transmission of the second-type random access message, the random
access response message including an uplink grant and an identifier
associated with the UE. The apparatus 902/902' may also include
means for using a radio network temporary identifier (RNTI) to
receive a response message associated with the two-step random
access procedure or the four-step random access procedure. The
apparatus 902/902' may also include means for using, while
operating in an idle mode or an inactive mode, a random access
radio network temporary identifier (RA-RNTI) to receive a response
message associated with the two-step random access procedure or the
four-step random access procedure. The apparatus 902/902' may also
include means for using a cell radio network temporary identifier
(C-RNTI) to receive a response message associated with a two-step
random access procedure while the UE is operating in a connected
mode.
[0142] In an additional or alternative configuration, the apparatus
902/902' for wireless communication includes means for determining
whether to perform a two-step random access procedure or a
four-step random access procedure based at least on a fallback
timer associated with the two-step random access procedure not
being configured. The apparatus 902/902' may also include means for
generating a random access message based on the determining, where
the random access message is one of a first-type random access
message associated with a four-step random access procedure and
including a preamble or a second-type random access message
associated with the two-step random access procedure and including
the preamble and a payload. The apparatus 902/902' may also include
means for performing a random access attempt by transmitting, to a
base station, the random access message. The apparatus 902/902' may
also include means for receiving, from the base station, at least
one parameter including one or more of a payload size, a set of
payload sizes, a Reference Signal Received Power (RSRP) threshold,
a path loss threshold, a fallback timer setting, a first-type
random access message transmittal count threshold, or a second-type
random access message transmittal count threshold. The apparatus
902/902' may also include means for determining whether to perform
the two-step random access procedure or the four-step random access
procedure is further based on the at least one parameter. The
apparatus 902/902' may also include means for measuring a reference
signal. The apparatus 902/902' may also include means for comparing
a measurement of the reference signal to the at least one
parameter. The apparatus 902/902' may also include means for
determining to perform the two-step random access procedure when
the measurement of the reference signal satisfies a threshold
associated with the at least one parameter. The apparatus 902/902'
may also include means for selecting the reference signal to
measure based on a predetermined rule. The apparatus 902/902' may
also include means for selecting the reference signal to measure
from among a plurality of reference signals received by the UE and
based on respective reference signal measurements. The apparatus
902/902' may also include means for determining to perform the
two-step random access procedure when the measurement of the
reference signal comprises a Reference Signal Received Power (RSRP)
of the reference signal and the RSRP of the reference signal
satisfies the RSRP threshold. The apparatus 902/902' may also
include means for determining to perform the two-step random access
procedure when the measurement of the reference signal comprises a
path loss measurement associated with the reference signal and the
path loss measurement satisfies the path loss threshold. The
apparatus 902/902' may also include means for measuring at least
one reference signal. The apparatus 902/902' may also include means
for comparing a measurement of the at least one reference signal to
the at least one parameter. The apparatus 902/902' may also include
means for determining to perform the four-step random access
procedure when the measurement of the at least one reference signal
does not satisfy a threshold associated with the at least one
parameter. The apparatus 902/902' may also include means for
receiving, from the base station, an indication that indicates
whether the base station supports a two-step random access
procedure, where the determining of whether to perform the two-step
random access procedure or the four-step random access procedure is
further based on the indication. The apparatus 902/902' may also
include means for determining whether to perform the two-step
random access procedure or the four-step random access procedure
further based on an access class associated with the UE. The
apparatus 902/902' may also include means for incrementing a
second-type random access message transmittal count after the
transmitting of the second-type random access message. The
apparatus 902/902' may also include means for determining whether
the second-type random access message transmittal count satisfies a
second-type random access message transmittal count threshold if a
response message is not received from the base station. The
apparatus 902/902' may also include means for determining whether
to repeat transmission of the second-type random access message or
to perform the four-step random access procedure by generating the
first-type random access message based on whether the second-type
random access message transmittal count satisfies the second-type
random access message transmittal count threshold. The apparatus
902/902' may also include means for performing the four-step random
access procedure by generating the first-type random access message
if the second-type random access message transmittal count does not
satisfy the second-type random access message transmittal count
threshold. The apparatus 902/902' may also include means for
determining whether to repeat the transmission of the second-type
random access message or to perform the four-step random access
procedure by generating the first-type random access message based
on a reference signal measurement if the second-type random access
message transmittal count is less than the second-type random
access message transmittal count threshold. The apparatus 902/902'
may also include means for receiving, from the base station, a
random access response message in response to the transmission of
the second-type random access message, the random access response
message including an uplink grant and information indicating a
failure to decode the payload of the second-type random access
message. The apparatus 902/902' may also include means for
transmitting, to the base station, a third-type random access
message comprising the payload based on the uplink grant, the
third-type random access message associated with the four-step
random access procedure. The apparatus 902/902' may also include
means for determining whether to perform another random access
attempt using the two-step random access procedure or the four-step
random access procedure when no response to the third-type random
access message is received or when a received response to the
third-type random access message indicates another failure to
decode the payload. The apparatus 902/902' may also include means
for receiving, from the base station, a random access response
message in response to the transmission of the second-type random
access message, the random access response message including an
uplink grant and an identifier associated with the UE. The
apparatus 902/902' may also include means for using a radio network
temporary identifier (RNTI) to receive a response message
associated with a two-step random access procedure or a four-step
random access procedure. The apparatus 902/902' may also include
means for using, while operating in an idle mode or an inactive
mode, a random access radio network temporary identifier (RA-RNTI)
to receive a response message associated with a two-step random
access procedure or a four-step random access procedure. The
apparatus 902/902' may also include means for using a cell radio
network temporary identifier (C-RNTI) to receive a response message
associated with a two-step random access procedure while the UE is
operating in a connected mode.
[0143] The aforementioned means may be one or more of the
aforementioned components of the apparatus 902 and/or the
processing system 1014 of the apparatus 902' configured to perform
the functions recited by the aforementioned means. As described
supra, the processing system 1014 may include the TX Processor 368,
the RX Processor 356, and the controller/processor 359. As such, in
one configuration, the aforementioned means may be the TX Processor
368, the RX Processor 356, and the controller/processor 359
configured to perform the functions recited by the aforementioned
means.
[0144] FIG. 11 is a flowchart 1100 of a method of wireless
communication. The method may be performed by a base station (e.g.,
base station 102/180 of FIG. 1, the base station 310 of FIG. 3, the
base station 404 of FIG. 4, the base station 504 of FIG. 5, the
base station 604 of FIG. 6, the base station 950 of FIG. 9, the
apparatus 1302/1302' of FIGS. 13 and 14, respectively, and/or the
processing system 1414, which may include the memory 360 and which
may be the entire base station 310 or a component of the base
station 310, such as the TX processor 316, the RX processor 370,
and/or the controller/processor 375). One or more of the
illustrated operations may be omitted, transposed, or
contemporaneous. In FIG. 11, optional aspects are illustrated with
a dashed line. The method provides for improved communication
between a UE and a network when a fallback timer associated with a
two-step RACH is configured. Aspects may improve the efficiency of
performing uplink synchronization between the UE and the
network.
[0145] At 1102, the base station provides an indication that
configures a fallback timer associated with a two-step random
access procedure, as described in connection with 610 of FIG. 6.
The providing of the indication that configures the fallback timer
may be performed, for example, by an indication component of FIG.
13. As discussed above, some base stations may support two-step
RACH while others might not. By providing the indication that
configures the fallback timer, the base station may indicate that
the base station supports a two-step RACH procedure and the base
station can guide the UE in selecting a way to initiate random
access with the base station. In some examples, the base station
may support two-step RACH on a UE access class basis. In some
examples, the indication provided by the base station may identify
the one or more UE access classes for which the base station
supports the two-step RACH procedure.
[0146] At 1104, the base station may transmit at least one
parameter associated with the two-step RACH procedure, for example,
to the UE, as described in connection with 610 of FIG. 6. The
transmitting of the at least one parameter may be performed, for
example, by a parameter component 1312 of FIG. 13. For example, the
base station may transmit one or more parameter(s) including a
payload size (and/or a set of payload sizes), a Reference Signal
Received Power (RSRP) threshold, a path loss threshold, a fallback
timer setting, a first random access message transmittal count
threshold (e.g., a msg1 transmittal count threshold), and/or a
second random access message transmittal count threshold (e.g., a
msgA transmittal count threshold). In some examples, the base
station may transmit the indication configuring the fallback timer
and/or the one or more parameter(s) via system information. In some
examples, the base station may transmit the indication configuring
the fallback timer and/or the one or more parameter(s) via
dedicated signaling to the UE operating in a connected mode.
[0147] At 1106, the base station receives a random access message
based at least in part on the indication, as described in
connection with 616 of FIG. 6. The receiving of the random access
message may be performed, for example, by the reception component
1304 of FIG. 13. In some examples, the random access message is a
first-type random access message including a preamble without a
payload (e.g., a msg1). In some examples, the random access message
is a second-type random access message including the preamble and a
payload (e.g., a msgA). In some examples, the random access message
is a third-type random access message including the payload (e.g.,
a msg3).
[0148] At 1108, the base station may attempt to decode the payload
of a second-type random access message, as described in connection
with 618 of FIG. 6. The attempting to decode the payload may be
performed, for example, by the decode component 1316 of FIG. 13. In
some examples, the base station may successfully decode the
payload. In some examples, the base station may unsuccessfully
decode the payload.
[0149] At 1110, the base station may generate a response message in
response to receiving the random access message, as described in
connection with 618 of FIG. 6. The generating of the response
message may be performed, for example, by the response component
1314 of FIG. 13. In some examples, the response message includes an
uplink grant. In some examples, the base station may generate the
response message based on the success or failure of the decoding of
the payload. For example, if the base station successfully decodes
the payload, the base station may generate the response message to
also include timing advancement information, contention resolution
information, and/or radio resource control (RRC) connection setup
information. In some examples, if the base station is unable to
decode the payload, the base station may generate the response
message to also include information indicating the failure to
decode the payload.
[0150] At 1112, the base station may transmit the response message
to the UE, as described in connection with 620 of FIG. 6. The
transmitting of the response message may be performed, for example,
by the response component 1314, the provision component 1318, the
failure component 1320, and/or the transmission component 1306 of
FIG. 13.
[0151] At 1114, the base station may receive another random access
message, as described in connection with 616 of FIG. 6. The
receiving of another random access message may be performed, for
example, by the reception component 1304 of FIG. 13. In some
examples, the random access message may be a retransmission of a
random access message. In some examples, the random access message
may be a third-type random access message including the payload.
For example, the base station may receive the third-type random
access message in response to the response message indicating the
failure to decode the payload of the second-type random access
message. In some such examples, the base station may then generate
and transmit a fourth-type random access message that is associated
with the four-step RACH procedure (e.g., the msg4).
[0152] FIG. 12 is a flowchart 1200 of a method of wireless
communication. The method may be performed by a base station (e.g.,
base station 102/180 of FIG. 1, the base station 310 of FIG. 3, the
base station 404 of FIG. 4, the base station 504 of FIG. 5, the
base station 604 of FIG. 6, the base station 950 of FIG. 9, the
apparatus 1302/1302' of FIGS. 13 and 14, respectively, and/or the
processing system 1414, which may include the memory 360 and which
may be the entire base station 310 or a component of the base
station 310, such as the TX processor 316, the RX processor 370,
and/or the controller/processor 375). One or more of the
illustrated operations may be omitted, transposed, or
contemporaneous. In FIG. 12, optional aspects are illustrated with
a dashed line. The method provides for improved communication
between a UE and a network when a fallback timer is not configured.
Aspects may improve the efficiency of performing uplink
synchronization between the UE and the network.
[0153] At 1202, the base station provides an indication of whether
the base station supports a two-step RACH procedure, as described
in connection with 610 of FIG. 6. The providing of the indication
may be performed, for example, by an indication component of FIG.
13. As discussed above, some base stations may support two-step
RACH while others might not. By providing the indication of whether
the base station supports a two-step RACH procedure, the base
station can guide the UE in selecting a way to initiate random
access with the base station. In some examples, the base station
may support two-step RACH on a UE access class basis. In some such
examples, the indication provided by the base station may identify
the one or more UE access classes for which the base station
supports the two-step RACH procedure.
[0154] At 1204, the base station may transmit at least one
parameter associated with the two-step RACH procedure, for example,
to the UE, as described in connection with 610 of FIG. 6. The
transmitting of the at least one parameter may be performed, for
example, by a parameter component 1312 of FIG. 13. For example, the
base station may transmit one or more parameter(s) including a
payload size (and/or a set of payload sizes), a Reference Signal
Received Power (RSRP) threshold, a path loss threshold, a fallback
timer setting, a first random access message transmittal count
threshold (e.g., a msg1 transmittal count threshold), and/or a
second random access message transmittal count threshold (e.g., a
msgA transmittal count threshold). In some examples, the base
station may transmit the indication of whether the base station
supports the two-step RACH procedure and/or the one or more
parameter(s) via system information. In some examples, the base
station may transmit the indication of whether the base station
supports the two-step RACH procedure and/or the one or more
parameter(s) via dedicated signaling to the UE operating in a
connected mode.
[0155] At 1206, the base station receives a random access message
based at least in part on the indication, as described in
connection with 616 of FIG. 6. The receiving of the random access
message may be performed, for example, by the reception component
1304 of FIG. 13. In some examples, the random access message is a
first-type random access message including a preamble without a
payload (e.g., a msg1). In some examples, the random access message
is a second-type random access message including the preamble and a
payload (e.g., a msgA). In some examples, the random access message
is a third-type random access message including the payload (e.g.,
a msg3).
[0156] At 1208, the base station may attempt to decode the payload
of a second-type random access message, as described in connection
with 618 of FIG. 6. The attempting to decode the payload may be
performed, for example, by the decode component 1316 of FIG. 13. In
some examples, the base station may successfully decode the
payload. In some examples, the base station may unsuccessfully
decode the payload.
[0157] At 1210, the base station may generate a response message in
response to receiving the random access message, as described in
connection with 618 of FIG. 6. The generating of the response
message may be performed, for example, by the response component
1314 of FIG. 13. In some examples, the response message includes an
uplink grant. In some examples, the base station may generate the
response message based on the success or failure of the decoding of
the payload. For example, if the base station successfully decodes
the payload, the base station may generate the response message to
also include timing advancement information, contention resolution
information, and/or radio resource control (RRC) connection setup
information. In some examples, if the base station is unable to
decode the payload, the base station may generate the response
message to also include information indicating the failure to
decode the payload.
[0158] At 1212, the base station may transmit the response message
to the UE, as described in connection with 620 of FIG. 6. The
transmitting of the response message may be performed, for example,
by the response component 1314, the provision component 1318, the
failure component 1320, and/or the transmission component 1306 of
FIG. 13.
[0159] At 1214, the base station may receive another random access
message, as described in connection with 616 of FIG. 6. The
receiving of another random access message may be performed, for
example, by the reception component 1304 of FIG. 13. In some
examples, the random access message may be a retransmission of a
random access message. In some examples, the random access message
may be a third-type random access message including the payload.
For example, the base station may receive the third-type random
access message in response to the response message indicating the
failure to decode the payload of the second-type random access
message. In some such examples, the base station may then generate
and transmit a fourth-type random access message that is associated
with the four-step RACH procedure (e.g., the msg4).
[0160] FIG. 13 is a conceptual data flow diagram 1300 illustrating
the data flow between different means/components in an example
apparatus 1302. The apparatus may be a base station. The apparatus
1302 includes a reception component 1204 configured to receive
uplink communication from UE(s) 1350 (e.g., as described in
connection with 1106, 1114, 1206, and 1214) and a transmission
component 1206 configured to transmit downlink communication to the
UE 1350 (e.g., as described in connection with 1102, 1104, 1112,
1202, 1204, and 1212). The apparatus 1302 may include an indication
component 1208 configured to provide to a UE, an indication of
whether the base station supports a two-step RACH procedure and/or
an indication that a fallback timer is configured (e.g., as
described in connection with 1102 and 1202). The apparatus 1302 may
include a RACH message component 1310 configured to receive, from
the UE, a random access message based at least in part on the
indication (e.g., as described in connection with 1106, 1114, 1206,
and 1214). In some examples, the random access message may be a
first-type random access message including a preamble. In some
examples, the random access message may be a second-type random
access message including the preamble and a payload. In some
examples, the random access message may be a third-type random
access message including the payload. The apparatus 1302 may
include a parameter component 1312 configured to transmit, to the
UE, at least one parameter associated with the two-step RACH
procedure (e.g., as described in connection with 1104 and 1204). In
some examples, the at least one parameter may include one or more
of a payload size (and/or a set of payload sizes), a RSRP
threshold, a path loss threshold, a fallback timer setting, a first
random access message transmittal count threshold, or a second
random access message transmittal count threshold. The apparatus
1302 may include a response component 1314 configured to generate a
random access response message in response to receiving the random
access message (e.g., as described in connection with 1110 and
1210. In some examples, the random access response message includes
an uplink grant. In some examples, the base station may generate
the random access response message based on the success or failure
of the decoding of the payload. For example, if the base station
successfully decodes the payload, the base station may generate the
random access response message to also include timing advancement
information, contention resolution information, and/or radio
resource control (RRC) connection setup information. In some
examples, if the base station is unable to decode the payload, the
base station may generate the random access response message to
also include information indicating the failure to decode the
payload. The random access message may be the second random access
message, and the apparatus may further comprise a decode component
1316 configured to attempt to decode the payload of the second
random access message and a provision component 1318 configured to
provide, in the random access response message, timing advancement
information, contention resolution information, and/or RRC
connection setup information, in response to the base station
successfully decoding the payload. The apparatus may include a
failure component 1320 configured to provide, in the random access
response message, information indicating a failure to decode the
payload of the second random access message, in response to the
base station unsuccessfully decoding the payload. The RACH message
component 1310 may be configured to receive, from the UE, a
third-type random access message including the payload based at
least in part on the information indicating the failure to decode
the payload.
[0161] The apparatus may include additional components that perform
each of the blocks of the algorithm in the aforementioned
flowcharts of FIGS. 11 and/or 12. As such, each block in the
aforementioned flowcharts of FIGS. 11 and/or 12 may be performed by
a component and the apparatus may include one or more of those
components. The components may be one or more hardware components
specifically configured to carry out the stated
processes/algorithm, implemented by a processor configured to
perform the stated processes/algorithm, stored within a
computer-readable medium for implementation by a processor, or some
combination thereof.
[0162] FIG. 14 is a diagram 1400 illustrating an example of a
hardware implementation for an apparatus 1302' employing a
processing system 1414. The processing system 1414 may be
implemented with a bus architecture, represented generally by the
bus 1424. The bus 1424 may include any number of interconnecting
buses and bridges depending on the specific application of the
processing system 1414 and the overall design constraints. The bus
1424 links together various circuits including one or more
processors and/or hardware components, represented by the processor
1404, the components 1304, 1306, 1308, 1310, 1312, 1314, 1316,
1318, 1320, and the computer-readable medium/memory 1406. The bus
1424 may also link various other circuits such as timing sources,
peripherals, voltage regulators, and power management circuits,
which are well known in the art, and therefore, will not be
described any further.
[0163] The processing system 1414 may be coupled to a transceiver
1410. The transceiver 1410 is coupled to one or more antennas 1420.
The transceiver 1410 provides a means for communicating with
various other apparatus over a transmission medium. The transceiver
1410 receives a signal from the one or more antennas 1420, extracts
information from the received signal, and provides the extracted
information to the processing system 1414, specifically the
reception component 1304. In addition, the transceiver 1410
receives information from the processing system 1414, specifically
the transmission component 1306, and based on the received
information, generates a signal to be applied to the one or more
antennas 1420. The processing system 1414 includes a processor 1404
coupled to a computer-readable medium/memory 1406. The processor
1404 is responsible for general processing, including the execution
of software stored on the computer-readable medium/memory 1406. The
software, when executed by the processor 1404, causes the
processing system 1414 to perform the various functions described
supra for any particular apparatus. The computer-readable
medium/memory 1406 may also be used for storing data that is
manipulated by the processor 1404 when executing software. The
processing system 1414 further includes at least one of the
components 1304, 1306, 1308, 1310, 1312, 1314, 1316, 1318, 1320.
The components may be software components running in the processor
1404, resident/stored in the computer readable medium/memory 1406,
one or more hardware components coupled to the processor 1404, or
some combination thereof. The processing system 1414 may be a
component of the base station 310 and may include the memory 376
and/or at least one of the TX processor 316, the RX processor 370,
and the controller/processor 375. Alternatively, the processing
system 1414 may be the entire base station (e.g., see 310 of FIG.
3).
[0164] In one configuration, the apparatus 1302/1302' for wireless
communication includes means for providing, to a User Equipment
(UE), an indication that configures a fallback timer associated
with a two-step random access procedure. The apparatus 1302/1302'
may also include means for receiving, from the UE, a random access
message based at least in part on the indication, where the random
access message is one of either a first-type random access message
associated with a four-step random access procedure and including a
preamble or a second-type random access message associated with the
two-step random access procedure and including the preamble and a
payload. The apparatus 1302/1302' may also include means for
attempting to decode the payload of the second-type random access
message when the received random access message is the second-type
random access message. The apparatus 1302/1302' may also include
means for providing, in a random access response message, an uplink
grant and at least one of timing advancement information,
contention resolution information, or RRC connection setup
information in response to successfully decoding the payload. The
apparatus 1302/1302' may also include means for providing, in the
random access response message, the uplink grant and information
indicating a failure to decode the payload of the second-type
random access message in response to unsuccessfully decoding the
payload. The apparatus 1302/1302' may also include means for
receiving, from the UE, a third-type random access message
associated with the four-step random access procedure and including
the payload based at least in part on the information indicating
the failure to decode the payload.
[0165] In an additional or alternative configuration, the apparatus
1302/1302' for wireless communication includes means for providing
to a User Equipment (UE), an indication of whether the base station
supports a two-step random access procedure. The apparatus
1302/1302' may also include means for receiving, from the UE, a
random access message based at least in part on the indication,
where the random access message is one of either a first-type
random access message associated with a four-step random access
procedure and including a preamble or a second-type random access
message associated with the two-step random access procedure and
including the preamble and a payload. The apparatus 1302/1302' may
also include means for transmitting, to the UE, at least one
parameter including one or more of a payload size, a Reference
Signal Received Power (RSRP) threshold, a path loss threshold, a
fallback timer setting, a first-type random access message
transmittal count threshold, or a second-type random access message
transmittal count threshold. The apparatus 1302/1302' may also
include means for generating a random access response message in
response to receiving the random access message, the random access
response message including at least an uplink grant. The apparatus
1302/1302' may also include means for transmitting, to the UE, the
random access response message. The apparatus 1302/1302' may also
include means for attempting to decode the payload of the
second-type random access message when the received random access
message is the second-type random access message. The apparatus
1302/1302' may also include means for providing, in the random
access response message, timing advancement information, contention
resolution information, or RRC connection setup information in
response to the base station successfully decoding the payload. The
apparatus 1302/1302' may also include means for providing, in the
random access response message, information indicating a failure to
decode the payload of the second-type random access message in
response to the base station unsuccessfully decoding the payload.
The apparatus 1302/1302' may also include means for receiving, from
the UE, a third-type random access message associated with the
four-step random access procedure and including the payload based
at least in part on the information indicating the failure to
decode the payload.
[0166] The aforementioned means may be one or more of the
aforementioned components of the apparatus 1302 and/or the
processing system 1414 of the apparatus 1302' configured to perform
the functions recited by the aforementioned means. As described
supra, the processing system 1414 may include the TX Processor 316,
the RX Processor 370, and the controller/processor 375. As such, in
one configuration, the aforementioned means may be the TX Processor
316, the RX Processor 370, and the controller/processor 375
configured to perform the functions recited by the aforementioned
means.
[0167] It is understood that the specific order or hierarchy of
blocks in the processes/ flowcharts disclosed is an illustration of
example approaches. Based upon design preferences, it is understood
that the specific order or hierarchy of blocks in the
processes/flowcharts may be rearranged. Further, some blocks may be
combined or omitted. The accompanying method claims present
elements of the various blocks in a sample order, and are not meant
to be limited to the specific order or hierarchy presented.
[0168] The previous description is provided to enable any person
skilled in the art to practice the various aspects described
herein. Various modifications to these aspects will be readily
apparent to those skilled in the art, and the generic principles
defined herein may be applied to other aspects. Thus, the claims
are not intended to be limited to the aspects shown herein, but is
to be accorded the full scope consistent with the language claims,
wherein reference to an element in the singular is not intended to
mean "one and only one" unless specifically so stated, but rather
"one or more." The word "exemplary" is used herein to mean "serving
as an example, instance, or illustration." Any aspect described
herein as "exemplary" is not necessarily to be construed as
preferred or advantageous over other aspects. Unless specifically
stated otherwise, the term "some" refers to one or more.
Combinations such as "at least one of A, B, or C," "one or more of
A, B, or C," "at least one of A, B, and C," "one or more of A, B,
and C," and "A, B, C, or any combination thereof" include any
combination of A, B, and/or C, and may include multiples of A,
multiples of B, or multiples of C. Specifically, combinations such
as "at least one of A, B, or C," "one or more of A, B, or C," "at
least one of A, B, and C," "one or more of A, B, and C," and "A, B,
C, or any combination thereof" may be A only, B only, C only, A and
B, A and C, B and C, or A and B and C, where any such combinations
may contain one or more member or members of A, B, or C. All
structural and functional equivalents to the elements of the
various aspects described throughout this disclosure that are known
or later come to be known to those of ordinary skill in the art are
expressly incorporated herein by reference and are intended to be
encompassed by the claims. Moreover, nothing disclosed herein is
intended to be dedicated to the public regardless of whether such
disclosure is explicitly recited in the claims. The words "module,"
"mechanism," "element," "device," and the like may not be a
substitute for the word "means." As such, no claim element is to be
construed as a means plus function unless the element is expressly
recited using the phrase "means for."
* * * * *